begging the question, language composition and orthogonality

Not too long ago, one of my friends used the phrase "begs the question" in the colloquial sense of "what we're talking about suggests that this other issue should be addressed".

And I've come to the point in my life where this doesn't bother me anymore, despite the fact that I know the technical rhetorical sense of "begging the question" -- an argument presupposing what it's trying to prove, often implicitly. I prove that unicorns exist thus: all those magical one-horned horses out there are unicorns. I prove that there's an objectively extant material world by kicking a rock and hurting my foot.

This post, of course, begs the question: will I be secure enough as an armchair philosopher to start using the phrase in the vernacular sense? I'm torn: there are few things I like less in the world than prescriptive grammar, but few things I like quite as much as precise, expressive expression.