It depends really, the more friendly the game/gamers are... the more I do find myself caring about ranks. ie, If I'm playing with some regulars and one of them says "Wahoo, level 58 now!" I will give my congrats, and actually mean it. Ranks really only hold any sort of value to me if it is friendly. When higher ranks help out the lower ranks, that's good.
What I don't like, is getting called a "noob" simply because the character I am playing is a low level, it doesn't make me any less experienced in the game, it simply means I haven't levelled that character well enough yet.
I personally see higher ranks as having more responsiblity, I hate high level folk who think that they should be praised quite simply because they've got more spare time than most. In the example of Diablo 2, I love helping people out quite simply because I can, lower level folk need high level folk to do runs and things for them, and I am happy to assist in those cases. I give away items that they're not likely to find until much later on, i'll clear the area of bad guys if someone dies and needs to retrieve their body, that's what being a high level/rank is to me.