A couple reasons. Nintendo is quality they only relase when it is 100% ready. Second they have so many titles they cant have a team working on every one at the same time. I would bet the development time is about the same as the other triple AAA games. Most take a minimum of 2 years
PS3, WII and 360 all great systems depends on what type of console player you are.
Currently playing Call of Duty Modern Warfare 2, Fallout 3, Halo ODST and Dragon Age Origins is next game
Xbox live:mywiferocks