Graduate Admissions: Teaching Emphasis
It's sort of a catch-22 situation here. On one hand, you do need a PhD to teach at the higher education level; on the other hand, the PhD doesn't teach (and doesn't even intend to teach) you how to teach!

But I guess wanting to teach (at university level) is a valid reason to get a PhD, as I've had friends and instructors who took PhDs because they want to teach college. Of course you'll still need to like doing research (and you'll probably still be held to the same admissions standards as those who just want to do research), but wanting to teach at the college+ level seems like a valid reason to take a PhD.

I'm not a faculty member, though, so you may want to talk to some teaching faculty with PhDs at your university to see what they think.