Why the Wii hate?

Wii hatred seems to come and go in waves. Right now, I don’t think there are too many people talking about how much they hate the Wii, and why it sucks compared to the competition. You can be sure that that sort of discussion will pop up right around E3. There will definitely be a lot of attention on Nintendo at the show, and there are bound to be people that feed off of Nintendo fan excitement in a negative way. What is it exactly that makes some gamers hate the Wii so much?