This is a really interesting question.
I've tried to find some sort of list of "banned" television shows, but I came up completely empty. You are of course right that many directors and producers have complained about movies being damaged by content ratings, but not television shows. I did find some possible reasons why though.
To begin, it's worth reminding ourselves what the ratings actually are:
TVY: "All Children."
This program is designed to be appropriate for all children. Whether
animated or live-action, the themes and elements in this program are
specifically designed for a very young audience, including children
from ages 2 - 6. This program is not expected to frighten younger
TVY7: "Directed to Older Children"
This program is designed for children age 7 and above.It may be more
appropriate for children who have acquired the developmental skills
needed to distinguish between make-believe and reality. Themes and
elements in this program may include mild fantasy violence or comedic
violence, or may frighten children under the age of 7. Therefore,
parents may wish to consider the suitability of this program for their
very young children. Note: For those programs where fantasy violence
may be more intense or more combative than other programs in this
category, such programs will be designated TV-Y7-FV.
TVG: "General Audiences"
Most parents would find this program suitable for all ages. Although
this rating does not signify a program designed specifically for
children, most parents may let younger children watch this program
unattended. It contains little or no violence, no strong language and
little or no sexual dialogue or situations.
TVPG: "Parental Guidance Suggested"
This program contains material that parents may find unsuitable for
younger children. Many parents may want to watch it with their younger
children. The theme itself may call for parental guidance and/or the
program contains one or more of the following: moderate violence (V),
some sexual situations (S), infrequent coarse language (L), or some
suggestive dialogue (D).
TV14: "Parents Strongly Cautioned"
This program contains some material that many parents would find
unsuitable for children under 14 years of age. Parents are strongly
urged to exercise greater care in monitoring this program and are
cautioned against letting children under the age of 14 watch
unattended. This program contains one or more of the following:
intense violence (V), intense sexual situations (S), strong coarse
language (L), or intensely suggestive dialogue (D).
TVMA: "Mature Audiences Only"
This program is specifically designed to be viewed by adults and
therefore may be unsuitable for children under 17. This program
contains one or more of the following: graphic violence (V), explicit
sexual activity (S), or crude indecent language (L).
Now, TV Guide actually did a report on these ratings, asking Does Anyone Care About TV's Content Ratings?. To quote some fascinating snippets from that article:
For most folks, the ratings bugs are just one more thing on an already
cluttered TV screen. According to a 2007 study by the Kaiser Family
Foundation, only 43 percent of respondents who had purchased a
V-Chip-equipped [content restricting] TV since 2000 even knew of the technology, and just 16
percent of parents said they utilized it. The study also found that
few viewers understood that "V" stands for "violence," "S" is "sex"
and "D" means "suggestive dialogue." Even more comical, a percentage
of parents polled thought "FV" — which warns of "fantasy violence" on
kids' shows like Cartoon Network's Ben 10 — is an abbreviation for
"family viewing." Oops.
So we can see that, unlike movie ratings which are fairly well known, TV content ratings aren't. There could be a few reasons for this, but I would argue the most likely is that movie ratings are extremely relevant for content released in the cinema or in stores as there are laws restricting what minors can purchase. Obviously many minors get their hands on these things anyway, but suffice to say restrictions are in place.
However, with TV Ratings it's much harder to restrict content. Whereas for movies the store is doing all the work in restricting content, for television the parent has to do the work. They need to set up the restriction software on the television and proactively use it. Many parents, who are perhaps not particularly technically savvy (thinking of my own mother here!) would struggle to do that. Without these restrictions, minors are free to watch pretty much whatever they want. Therefore, unlike with movies where a director may feel the change of rating has affected his overall "vision", with television series the creators may feel they are still hitting the "target audience" and therefore their vision hasn't been compromised.
Anyway, that is just a minor point and a theory to boot, but I thought I'd suggest. More importantly from that TV Guide article though is this:
Critics are mixed on how effective the system has been. Children Now
national policy director Jeff McIntyre gives "50/50" marks to the
ratings. "There are a lot of concerns about how the ratings are
implemented and significant concerns about the consistency of the
ratings," he says. "A show on CBS will have different ratings than a
similar one on NBC, or shows in syndication have different ratings."
"The movie ratings system tends to get a little more press and social
awareness, and tends to get integrated as a marketing mechanism,"
McIntyre says. But in comparison, TV content ratings rarely, if ever,
get a rise out of producers or viewers. That's mostly because the TV
networks rate themselves, via their internal standards and practices
departments. Plus, in the movie world, a rating can impact box office,
as many theater chains won't show unrated or NC-17 movies, and are
strict about not letting kids into R-rated features.
"We could rate a show TV-MA [mature audiences only] and it's still
going on the air, even if the affiliates don't like it," says a
network exec. "There's no crossing guard in TV. If a 12-year-old
watches a TV-MA show on TV, that's on the parents." There is an
oversight board that serves as a clearinghouse for TV content ratings
issues, but McIntyre says it's still difficult to figure out how to
dispute ratings. "It's such a broad TV rating system, there's not a
lot of clarity who you can go to if you have a complaint," he says.
So you can see that it is being argued that as networks are self rating, it's nowhere near as important for them to "fit" their show into a certain rating. If the show is too violent or sexual, they can simply label it suitable for Mature audiences and release it.
The article then continues, stating:
Critics had feared that the content ratings might give networks
license to get dirtier, and McIntyre believes that early on, a handful
of shows took advantage of the system to prove how "edgy" they were.
The pilot to CBS' 1997 Steven Bochco drama Brooklyn South earned a bit
of notoriety for being the first broadcast program to land a TV-MA,
but that show didn't last long. Since then, Loesch says she doesn't
think "there was any real purposeful effort to use ratings as a shield
to get away with anything. There were a lot of naysayers and I think a
lot of their predictions have never borne out to be true."
Loesch adds that even though she regularly hears from parents
concerned over language and the sexualization of young girls in TV,
that doesn't extend to the content ratings. "To tell you the truth I
don't hear anything about the TV ratings," she says. "It's not a part
of the conversation. The content itself is."
So again any "naysayers" appear to be complaining about what content is allowed to be shown, rather than the actual rating system. This suggests that producers/directors are quite at ease to create the show they want to create as they know a Mature rating can be given to it if necessary and the show will still be broadcast to a nationwide audience.
On a final note, I haven't found any shows that were so unsuitable that they weren't released. But this seems logical to me. Whilst I know there are banned movies, it seems difficult to imagine how a network could pay for a show that was so extreme it could never be released. If that happened, I would imagine the show's creators could be in legal difficulties. After all, for filming to go ahead the idea for the show, along with its content, would need to be agreed and verified. If they changed this to make it far more extreme/sexual/graphic/something, they would be validating that agreement. Not to mention the fact that the channel creating the show would be keeping track of it during production and would be able to "yank" it long before it go to air (e.g. if the pilot was unsuitable, nothing else would be commissioned).
I'm aware that article I've used primarily for this answer addresses the efficiency of content ratings as opposed to TV show-runners criticizing the ratings. But I hope it is still useful to you. It appears that directors/producers simply don't view the ratings system as much of an issue, compared to their counterparts in the movie business.