I remember the Nintendo v Sega days and the Nintendo v Sony days. I think the issue is that most Wii owners don't. It certainly seems like most people here are too young to remember the SNES, or even the N64.
I don't think people who weren't around in those days really understand the complaints that people are beginning to direct at Nintendo. People who didn't play Chrono Trigger, A Link to the Past, Secret of Mana, A Link to the Past et al probably haven't noticed what Nintendo has lost over the years. Likewise, people who have only played Ocarina of Time or Mario 64 with the benefit of hindsight don't understand how utterly charming those games were for people at the time.
It's a difficult thing to quantify, but something has changed since Nintendo began actively competing in the videogame market. After the PSX became the 'cool' console, Nintendo tried too hard to be completely different. The Gamecube suffered as a result of Nintendo trying to differentiate itself, but not going far enough. I think the Wii has failed (although certainly not in a commercial sense) because Nintendo has gone too far.
I can't help but feel the company has sold out my childhood a little bit with the Wii. That spark that made Nintendo games special is well and truly gone. Even the classics like Mario and Zelda have been watered down to suit non-gamers. I don't know if it's really happening or if it's just nostalgia, but it certainly feels like the magic has died.