Quote Originally Posted by Marcus View Post
Should a v-w distinction be mentioned in a textbook of English or not?
That depends. Is it a textbook for academic study, say year 1 in a series that's supposed to last you throughout school, or is it a book for people who are visiting England in a month's time and don't know any English at all?

If it's the former, then yes, of course it should. If it's the latter then possibly not.

Why do you care so much about the conjugation
I don't care about it. I've just found that getting grammar wrong is far more likely to result in blank stares or misunderstandings than having a funny accent, so I give more thought to the former than the latter.