Obviously people are going to favor one company or one console over another. That's inevitable.
But I have been struck by the amount of venom directed at Nintendo on sites like IGN and GameSpot, and even here where posters are infinitely more intelligent and more reasonable.
I would really like to get to the heart of the issue. And I don't think it's just because of the success of Wii, which I imagine rubs many video game players the wrong way since the Wii succeeded by winning over the hearts and minds of "amateur" video game players. In other words, the Wii won because it embraced everything video game hardware and software should NOT be.
But the issue is older than that. SNES, however great, was usually considered the less "cool" system. N64 darkened in the shadow of PS1. And GCN was a punchline. So Nintendo has been mocked for about 20 years, for being "kiddy," for being "out of touch," and, most recently, for inviting in a group of novice fans unworthy of membership in the brotherhood of video game veterans.
So why do some people despise Nintendo? Two reasons, I think. One is elitism, which teaches that Nintendo games and fans are part of a lower social strata. And the other is custom: people hate Nintendo because it is fashionable to hate Nintendo.
I would suggest this to those that spend a disproportionate amount of time belittling Nintendo and it's fans: use that time and energy to rent and play a few Nintendo games; you might actually like them.