Perhaps it's a little confusing in certain cases, but it's probably not worth changing at this point; it's been our name for quite a long time and as far as we know hasn't caused any large issues.
The summary is that for a very short period of time, StackExchange let newly launched sites pick cute names, and was going to let them be used as domain names. Very quickly they thought better of this, and still let them be used as titles/taglines, and then eventually decided to stick with obvious titles as well. There was of course a lot of debate and drama at every stage of this process. There are now a few exceptions (askubuntu, arqade...) but I think they're generally reserved for cases where they think unique branding will help the site. At this point, unless there are some really convincing reasons, I think everything's going to stay the way it is.
As for the question in the title, I wouldn't say it's misleading (I don't think anyone has any doubt we're a cooking site), but it does I suppose in some cases reduce discoverability as you found. The search in the dropdown does still bring it up for "cooking", though it doesn't for "food" - if you want to post a question asking for that, it's probably a good idea. (I'm not particularly worried about it being discoverable via "gastronomy".)
Some further reading: