Clint_L
Legend
My pet peeve is languages like "dwarvish" and "orcish." Languages don't really work that way. That's why there are no "humanish" language. So I resolve it pretty much as OP states: languages are regional and there are a lot fewer of them that are widespread, and then maybe distinct languages for isolated communities. However, I think Common actually makes sense - in a setting with as many distinct sentient species and cultures as D&D supposes, I imagine there would be a lot of pressure to come up with some mode of near-universal communication.
That said, realism is seldom my main rationale for gameplay decisions in D&D, since the premises of the entire game are so wildly unrealistic in so many ways that there isn't much point in picking any one hill to die on - it's whatever floats your boat. Occasional, a language barrier becomes a plot point but there's no way I would, as some do, have party members struggle to talk to each other because of language challenges. That just doesn't seem like much fun at the table - am I going to refuse to let those players talk and plan together on the premise that their characters couldn't? I feel like it would harsh the vibe.
That said, realism is seldom my main rationale for gameplay decisions in D&D, since the premises of the entire game are so wildly unrealistic in so many ways that there isn't much point in picking any one hill to die on - it's whatever floats your boat. Occasional, a language barrier becomes a plot point but there's no way I would, as some do, have party members struggle to talk to each other because of language challenges. That just doesn't seem like much fun at the table - am I going to refuse to let those players talk and plan together on the premise that their characters couldn't? I feel like it would harsh the vibe.