There are indeed comments from various of the filmmakers why they went in this direction. The overall tenor of those comments has been nailed by you in the question already, though. It was for the same reason that Ra's Al Ghul's regeneration and resurrection abilities have been reduced to trickery, allusions and a mere philosophical immortality of his presence and why various plot elements and characters were changed from the source material. To bring him more in line with the movie's style, atmosphere and setting. Nolan's take on Batman is centered around a very realistic and serious imagining of that whole universe, like all this could actually exist easily in our own reality.
You certainly hit it on the head when you say "the Bane in comics was hilarious". Especially the whole Venom aspect is way too over-the-top for this. While the movies might really scratch the edge of technological plausibility at times (stupid cell-phone radars anyone?), they are far from the domain of Science Fiction or Fantasy, not only regarding the tech, but the whole style and presentation as very serious crime thriller dramas. Sure, the Venom aspect is not too fictitious, but the whole depiction of a half-naked muscle machine driven by huge tubes pumping his body full with some magical super-soldier serum is just a bit too over-the-top to fit into the serious and realistic universe we've been presented so far.
David S. Goyer: I first brought up Bane and Chris was initially horrified. And I said "Hold on, hold on, hold on." This will be the Nolan version of Bane.
Christopher Nolan: His appearance in comics is very fanciful and wouldn't work in my opinion, in our world at all. So we needed to find the Dark Knight Rises version of what that would be.
However, they didn't change him completely, they merely adapted him to the movie's setting:
In his answer Chad already alludes to the fact that even the comic Bane was quite intelligent.
His background as a man grown-up in prison is still there (even if his geographic origin was altered).
Even if the movie Bane might not be as pumped as his "hilarious" source material, his physicality is still a major aspect of him. He is quite a heavy chunk of a man who easily trumps Batman in a physical fight and who doesn't hesitate to show us his muscles. And this was the primary motivation for choosing Bane in the first place.
Christopher Nolan: In trying to cast the villain, trying to decide who the villain would be it was very important to me that it be a physical force. And a very directed militaristic force. And Bane seemed the ideal character to take on the physical threat to Batman.
David S. Goyer: He's a creepy very physical character. Somebody who's been physically distorted.
Christian Bale: Obvously wanting to make sure that physically Bane is superior. And this is the first time that Batman has come across anybody who is superior.
The Venom aspect also was not entirely dropped but just heavily toned down into a mere face-mask supplying him with anaesthetics or painkillers. And you could actually argue that those painkillers/anaesthetics are indeed giving him unnormal strength and endurance in the way that increased tolerance to pain enables you to go far beyond your normal capabilities. So it is pretty much a realistic interpretation of Venom.
He might not look like a "Mexican wrestler", but his mask is still an important and menacing feature of him, even if adapted a bit to his supposedly militaristic background and its functionality regarding the adapted Venom aspect. Add to this also the not to underestimate fact that in a movie seeing the actor's eyes gives him much more ways for expression and can add way more to his presence than a weird mask.
Christopher Nolan: We knew we wanted the mask, but we wanted it to have more of a militaristic military hardware sort of feel to it. And a sense of it having a practical application even when it's got a menacing appearance...We talked a lot with Tom about this, about which parts his eyes and eyebrows and stuff he wanted to be able to use to be expressive.
Emma Thomas: It makes Bane that much more scary frankly, that you can read in his eyes the passion with which he wants to take down Gothan and Batman.
As to the clothes they are also less "hilarious" or "fanciful" but more functional, emphasizing his militeristic/mercenary background but also playing a little with the revolutionary aspect.
Christopher Nolan: We wanted him to look like a mercenary, like a military man. Somebody that you could believe would storm into an environment with his men and present a very very real threat...There is also an element of what I'd call "romaticism" to him. The Tale of Two Cities thing we're trying to get in there with Bane.
Lindy Hemming: The whole idea that he's a revolutionary of some sort that's gone wrong. So the coat is taking a sort of Swedish Army coat, which is the first thing I saw. And trying to give it a French Revolution period coat shape a little bit as well.
So I hope you can see that this is still Bane at his very core, but adapted into the universe of the trilogy, like all the other characters afterall. And we wouldn't want to see this in a Nolan-movie ;-):
All the filmmakers' quotes in here are taken from the BluRay of the movie.