The question calls for an objective response, so I will leave opinion out of this:
1) It's in first. Being a winning console, it garners hate from fans of other consoles.
2) It's not HD. I don't really understand this one, but it's there.
3) It has quite a few low-quality games that sell and high-quality games that don't sell. Also some high quality games which sell and low-quality games that don't, but nobody ever remembers the good things.
4) The Wii install base is made up of Nintendo fans and casual gamers. Casual gamers don't post on the internet. Nintendo fans aren't overly common after last generation.
Why it doesn't get many third party games:
1) Most third party games don't sell particularly well on Wii (the exception being...how do I explain this without saying the word "casual"?), compared to the HD consoles. In fact, many "casual" (not a very accurate word) games actually sell better on 360 than Wii. Third party games in general sell better on HD. Actually, this applies to every Nintendo console from the N64 onwards. First party games ALWAYS sell the best, on Nintendo systems.
2) The HD has a larger install base than the Wii. Because the two HD brothers (not twins) have similar capabilities, it is fairly simple to develop for both. To make a Wii version is to make a version which is graphically inferior and has a different control scheme.
When you bring the two together, a developer making a Wii game is putting effort into making a new version different from the other two, which may or may not sell as well as, and make as much profit as, the HD versions. This isn't helped by the fact that many third party games on the Wii are badly made ports, and those that aren't (NMH, MadWorld, The Conduit, Zack and Wiki) tend to be...not commercial failures, but not huge sellers on the level of Ninty first party games like Mario and Wii Fit, or large third party HD games, like Halo, GTA and CoD.
EDIT: Oh, and before somebody says I'm trolling (I know it will happen), I challenge you to find something in my post which is untrue or irrelevant, these being the two types of trolling.







