I'm not about to say it's a conspiracy, but I think all the Wii hate stems from both a lack of understanding about this new shift in the gaming industry and a dislike for some of the side effects of the shift.
First off, some people don't understand that every market must be stabilized. We're seeing a glut of casual minigame stuff on the Wii because it's easy to produce, and everyone wants to nab their piece of the casual market pie, and make a name for themselves (or generate a quick buck) before the casual market settles. By "settles" I mean, the casual gamers rest on their selections and stick with them more or less forever. Nintendo and EA are doing a great job of establishing themselves as the companies of choice for fitness and exercise games.
This frenzy, of course, results in a lot of games taking up shelf space that are just plain unappealing to conventional gamers. The frenzy peaked back in 2007-08, when there wasn't much coming out of Nintendo that appealed to the hardcore crowd and everyone else was releasing some terrible software. Sony seemingly had the same problem (some may argue they STILL do), regarding a dearth of great software, but then you won't find Chicken Shot on their console, either.
The second point, about disliking the new software geared towards casuals, goes a little deeper. Basically, people don't want to be associated with Chicken Shot, Anubis 2, or Ninjabread Man, because in their minds, just the fact that the Wii has these games for purchase means the console itself is made worse. It's basically an evolution of the "Nintendo is a kiddy console for kids" thing that the GameCube picked up. Moreover, since the Wii doesn't have the graphical power behind it as the 360 and PS3 do, a lot of the hardcore market doesn't think that even the good games are any good, because they don't LOOK as good. It can be argued that it's the natural result of pushing visuals for years and years.
These same fanboys are, of course, creaming their jeans over Natal and Sony's glowstick, thingies. This implies a rather acute sense of jealously about the Wii's success over the supposedly "better" consoles. Oh well.