To be honest, I like games that are "fun". The only drawback to the more casual crowd is someone keeps mixing up the word "fun" with the word "easy". However, I must admit that I didn enjoy playing my first Zelda where I actually found all the Heart Pieces and the first Mariuo where I was able to collect all the stars, neither with an FAQ. Personally, I feel the wii library is just large enough to keep gamers entertained as long as they are not picky about the genre, with titles like Metroid, Zelda, Mario Galaxy, World of Goo, Smash, Mario Kart, Paper Mario, and Okami. Unfortuantely, this does not compete with Xbox is quantity, where a First Person Shooter fan has double that list for a single genre.
There are multiple reasons why the wii's library is sub-par:
1. All the third parties mis-judged who the market leader would be, and require about two years to develop a game.
2. They try to capitalize on a "casual" market who they believe to have no knowledge of gaming, and thus can be easily appealed.
3. Publishers do not know what will sell on the Wii, but guessed that minigames were a good choice, and believe hardcore games won't sell.
4. Developers dislike the Wii. It's inferior graphical capabilities limit what the developer can do, while it's motion controls require creativity and innovation, while the Xbox can sell games that follow traditional formulas.
5. Nintendo went through all it's best frachises fairly quickly, and needs time to remake them. It has single-handedly dominated it's own sales chart entirely with first party games, which while impressive, means that they have exhausted their frachises somewhat, and need more time for developement.
6. Because of low developement costs and a high install base on the wii, games that flop can be marginally profitable.