Yes...and tone of voice is important too. Some people have a really sexy tone of voice.
Well yeah, it's because people who are intelligent and can articulate their words eloquently are more interesting to talk to. So I agree with you that a well-spoken person is infinitely more attractive than a ditz or dumbass. I can't stand talking to people who say "like" every other word or just babble on. I prefer quality over quantity, with anything.