I find it a bit annoying to see people who don't have this kind of problems complain about, in effect, having to see a handful of questions they personally don't find interesting. Java questions do not prevent anyone from talking about Excel or Python on Stackoverflow. And we have a lot of great answers to visa/residence permit questions, it's not like they create special difficulties as your comments would seem to imply. Objectively, that's the one expertise we do have at the moment (at least for some part of the world).
It's true that we could do with more questions about other aspects of life in another country but I have not seen many good questions or answers about that. One very clear requirement of the Stackexchange platform is that we don't want to turn this into a forum. "Dialog" is not what we want and the best questions should in principle have an objective answer (a solution to a problem, not various opinions on a topic). That's why questions about dealing with a foreign culture are actually more problematic than visa questions.
Most importantly, what we have is clearly too few rather than too many questions, what actual problem would yet another split solve? Visa and immigration questions are explicitly on-topic and this site was created in large part to handle them (because travel.SE did not like them). Anybody who wishes for something else is free to go through the usual site-creation process and see if they can get anything done but why should people who are interested in visas and the like take care of this or let you hijack this site? I don't think getting rid of the bits that actually work is going to make it any better.
Incidentally, questions about voting abroad, dual citizenship, etc. are in fact very similar to visa questions in that they require some legal expertise (or at least raise legal problems) and we actually have plenty of those! In practice, the ones that we don't really know to handle right now are questions about taxes and running a business between two or more countries.