In Jiro dreams of Sushi (2011), director David Gelb could have used an interpreter for the interviews to present the information in English. Instead, the whole documentary is in Japanese with English subtitles. Why do you think that the director took this approach?
As it's been pointed out in the comments, dubbing a documentary about a Japanese chef, in an all-Japanese setting, would seem a bit "off". Furthermore, it seems to matter even more for director David Gelb, as his Twitter account greets you with the following pinned tweet:
@ThisIsDavidGelb - Please turn on original audio and subtitle in the settings! The show is not meant to be dubbed.
The tweet refers to his show Chef's Table, the episodes of which presents a variety of chefs from all around the world; hence, it is likely that Gelb thought of the same for his Jiro Dreams of Sushi movie. In another tweet, he explicitly stated he preferred the subtitles:
@ThisIsDavidGelb - Thanks so much for watching Chef’s Table and for all of the feedback! For those who prefer subtitles to the dubbing, you can switch the audio to the original language and turn on subs in the @Netflix app. (poll reads 86% subs, 14% dubs)
@victormarkwhat - Thank you! This is great to know. I just came across your twitter because we were watching Chefs Table S4:E2, did not like the dubbing. We were wondering if anybody else felt the same. Much better with subtitles!
@ThisIsDavidGelb - Seems most prefer the subs, as do I.