It has nothing to do with the genres, these titles are merely broken or imperfect. You can not weigh in novelty, you look at wii sports compared to other sports titles and will see how much depth they lack and the amount of things to unlock, options, etc, are incredibly limited. Titles like mario party are rarely recoated with anything worth a damn. Reviewers will review games based on things they have experienced. Games like viva party animals and fuzion frenzy 2 also tanked in reviews because of the FLAWS they have, nothing to do with wii.
If viva party animals had robust and amazing online, incredible single player and multi, etc etc, im sure it would score well. Look at brawl, it is a party title with a strong campaign and some form of online, care to guess how well it will sell and review?
Reviewers won't factor wii games any differently, if the novelty somehow makes the game that much better, sure, but reviews merely break down the qualities of each title, just as pixar movies can review high like big more adult block busters, wii games can review high when developers decide to make full level production products.
But you don't give wii sports a 10 in graphics when a thousand other games on the same platform kick its ass in graphics, you don't give wii sports an awesome score for depth in gameplay when all you do are the same few actions, just as you don't score mario party 8 high when the controls don't work at times. Look at how rock band and guitar hero do in comparison, full fledged titles WITH a novelty to boot.
Note: Some games in my collection are no longer owned, but have owned.
