Or *gasp* they just don't like the game. Just because something's polished to hell and back, offers uniquely interesting gameplay, and has a lot of fans, doesn't mean the majority will take a liking to it.
And you're right...gamers are jaded nowadays...partly because they have so much more choice. Back when Nintendo 'could do no wrong,' you didn't as many choices in games across so many competing, equally-viable platforms....at least, nothing like it has been since the 32-bit console era.
I understand the idea that gamers are superficial...video games are a largely visual medium, always have been. If it doesn't grab you by its looks and you've got other choices (on that platform or others), you probably won't stick with it. When you're younger, you don't usually have much choice in what you're 'stuck' with, as far as a gaming platform and maybe even the games. So, you have to play what you have.
When you're younger, you are more easily-impressed and sucked into games. I think that's a big part of why Nintendo's games are largely very similar to what they've done in the past and it tends to skew younger...it works for that age-group...not saying that Nintendo's stuff is teh kiddy, but really...they go after that market with a vengeance...always have.
Of course, this is all just my opinion.