I believe that Nintendo and Sony fans are simply more vocal. This is because of how old the companies are. Sony has been in gaming since like... 94? 95? There are a LOT of people who grew up with X, Triangle, O, Square, Crash Bandicoot, and Cloud Strife. Many gamers (possibly most gamers) played their first game on a PS console.
By the same token, a lot of people started gaming with the NES, SNES, GB, GBA, N64, or maybe even the Gamecube. When something was a part of your childhood like that, it grows to an elevated status. You have nostalgia wrapped up in it. You remember staying up late in your room playing Pokemon, arguing with your brother over a game of Tekken, that feeling when you beat your first game... etc.
By comparison, the XBox entered the market in like 2000, and it wasn't very popular, especially among younger gamers. If someone got an XBox 360 when they were 5 (unlikely as they more likely got a Wii), that person is 13 now, and they're not very likely to be posting in forums like this. If someone started gaming at 10 with the XBox, then they're now 18. That's around the age that they'd post around here, but most people who were ten when the 360 came out probably had another console beforehand.
So, yeah. I think nostalgia is a large part of why Sony and Nintendo fans are a bit more passionate. Nintendo's not just a gaming company, they're a part of my childhood, so if you insult them, you'd best expect to get an earful :)







