"HDTV does not make anything look better."
Um, yeah. If the content, whether game, dvd, or television, is created for HD, it definitely looks noticeably better than SD content.
Will an HDTV make standard def content look better? If you have an upconverting DVD player, yes; I don't think that works for the games.
I would hope all the games for PS3 and Xbox360 would be 'downconvertable' and playable on 480i/p sets, but it doesn't sound like that's universally the case.
Obviously I'm sure there are some games that spent more time and money on the graphics than the game content/story; 1080p crap is still crap.
Wii doesn't support HD resolutions at all, I don't think. Does it support widescreen tv's?