I think I know what you mean and will come to that in a bit*. First I do want to point out that to some of us "nappy" is not a word that means unkempt, uncared for, ugly or matted. I use the word nappy in the English sense of the word, which is nothing more than tightly coiled or curled. It is a synonym for kinky which also mean tightly coiled/curled. You can look it up if you like (
www.onelook.com) and you will see most of the reputable sources do not consider the adjective "nappy" as derogatory.
The idea that nappy meant uncombed hair came from 400 years of slaves not having a comb--slaves who had 4B hair. Someone recently reposted the links on that and I will give them to you in a bit for your convenience. Basically, because anyone with "tightly coiled/curled" hair could not comb their hair when they landed in this foreign land coz no combs were made for that sort of hair and they didn't get to pack, then anyone with that sort of hair ended up with unkempt hair due to not having any means to groom it. In other words, if you had nappy hair, you had no way to groom it so it was not a nice thing to look at. So in time, having nappy hair became something no one wants to have. And in turn, the word "nappy" was inferred to mean "gross" when it really has the most innocent meaning in the world.
*Now you make a good point about nappy hair looking unkempt. I do agree that many people do not wear their nappy hair in ways that make it attractive. Laziness might be part of it--like Jay Z not combing his hair when I've seen it combed before--but it could also be not knowing how to care for 4B hair. Also type 3 hair is the sort of hair that has been worn natural in this country so much more than type 4 hair, so that type 3 styling methods are what's easily available. Some type 4 hair can duplicate those looks, but hair like mine will end up looking uncombed if I tried a WNG. Close up, I'd have very pretty coils but from far, it doesn't look combed. Add to that the fact that it doesn't reflect light like type 3 hair so doesn't shine as much and you can see how unless I embraced styles that work for my hair, I will get that funny look from those who don't really understand my hair.
My hubby liked my hair relaxed and wasn't too keen on 4B hair. But now he absolutely likes my hair. It was all in not understanding it and not believing it can grow and not seeing it worn in ways that brought out the beauty in it. Now he'd kill me if I dared relax, not that I want to. But he really appreciates my hair.
So I think it's all just a matter of educating folks and also exposing them to natural hair that looks beautiful, not because it is mimicking another type, but because it's actually exploring the many unique styles it's capable of.
OK, nuff rambling; here are the clips that shows you how "nappy" came to be viewed something to be dreaded and totally misunderstood to mean something negative:
400 Years Without a Comb
Part 1:
http://www.youtube.com/watch?v=4cMf1heTa6A
Part 2:
http://www.youtube.com/watch?v=winJvvYCS20
Part 3:
http://www.youtube.com/watch?v=CvMvNgFJ8zU
Part 4:
http://www.youtube.com/watch?v=tRwLkS7W4oM
Part 5:
http://www.youtube.com/watch?v=p-FBFIA1Hks
Part 6:
http://www.youtube.com/watch?v=rbXLbZhivOM