My parents (neither one a native English speaker) don't like saying "you're welcome" because to them it sounds arrogant. That's not to say that they pass such a judgment on anyone who uses the expression, or even to say that they never use it themselves; they just can't bring themselves to say it without some level of discomfort.
Quirky as I initially found this fact, I realized that I don't say it much either. It feels cumbersome compared to "my pleasure" or the entirely informal "no problem," and I always find myself stumbling over the syllables like a shy little boy. Maybe I inherited a dislike of the phrase from my parents. Maybe I just inherited the set of values--or quirks--that make it so awkward for them.
My dad's explanation for his dislike of the phrase in question has to do with humility: by saying "You're welcome," the person receiving thanks acknowledges his/her entitlement to recognition for an act of kindness, and in so doing creates a two-tiered system with the obliged at bottom.
As opposed to the Portuguese/Spanish version my parents are used to ("de nada," which translates roughly into "it's nothing" or "think nothing of it"), "you're welcome" implies a commitment. If one is to "think nothing of it," the transaction is terminated almost as quickly as it began; but to what does the giver "welcome" the recipient? More charity? Whereas "think nothing of it" humbly rejects accolades, the acceptance expressed by "you're welcome" seems self-aggrandizing.
Maybe it's far-fetched to extrapolate from this the notion that a polite idiom would have a sinister effect on the way English speakers give and get thanks, but there's something a little creepy about the self-congratulation involved in some of the louder American efforts to help Haitians, isn't there? In the weeks following the earthquake, every hour on CNN was filled with reports on Haiti that shared time with the network's anchors and correspondents lauding themselves for doing such a great job.
Understand, I don't mean to denigrate the good that people have done, only to comment on what I think is a disturbing undercurrent of charity in general and American charity in particular. CNN's sentimental, self-congratulatory drama annoyed me a bit, but it's a superficial sort of annoyance. Much more disturbing and telling in this regard (as Naomi Klein of course has already pointed out) is that amid all the good deeds and goodwill, the harbingers of disaster capitalism have been licking their chops since day one. And that's not just my opinion. So, you're welcome, Haiti.