I used to have no problem with point-buy rules when creating ability scores. Now, having run a campaign where the PCs were all given a generous (25-point in Pathfinder) point-buy build, I'm beginning to dislike point-buys.
I believe that they do encourage min-maxing, as most of the characters my players play have started with a score of 20 in their most relevant attribute (e.g. the fighter with 20 Strength, the alchemist with 20 Intelligence), etc., via racial ability bonuses on top of point buy. I thought that might simply mean that I'd been too generous with the point-buy allocation, but my players flat-out told me that they were going to put 20 into their "prime requisite" (to use an older term) no matter what.
As I see it, the main draw of point-buy is that it lets you perfectly tailor a character around a specific idea that you already have. If you want to play a wizard, you can make the right stats for a wizard, instead of randomly rolling up a character that'd make a better fighter.
However, I do think that they lend themselves to mix-maxing, at least moreso than random generation does. I've also found myself liking several ideas I've recently read on various OSR blogs (most notably Grognardia; forgive me for not posting a link), stating that Pathfinder/D&D is a game, and that the game begins when you first sit down to make a character, not when the first adventure begins - in other words, that character "generation," rather than character "creation" - is part of the game-play, random die rolls and all.
I personally also feel that it allows for a greater bit of in-game verisimilitude to roll your stats, since in real life you can't decide how wise or how healthy you'll be (to a degree; I recognize that in real life you can change your physical and mental state somewhat via work and self-improvement, but D&D doesn't allow for that level of nuance).
So yes, I feel that point-buy should be discouraged. I'm all for it being listed as one of the alternate options for making a character...preferably several listings behind various dice-rolling methods.