though i tend to agree with you on the most part multi-player mode can get old too. i mean after 2 hours of wario with 6 people you end up just playing the same games and the whole shock/surprise of the games have worn off. i Did like Wario Ware and i still play it even on single player..but it seems more often than not that my friends tend to get tried of minigame games rather quickly. could be from their stoner attention span.
but regardless of that i do agree its not so good to judge a mostly multi-player game on its single player mode, but in the case of Wario and Rayman its necessary to beat single player mode at least once to get multi-player mode in full swing, so judging that in its self is totally cool.
Also....Jeez don't be so wound up