The obvious answer to "where did the Wii go wrong?" would be "nowhere" because it's evidently making Nintendo more money than... oh, any end to that sentence is going to sound like a Yahtzee ripoff and I'm nowhere near enough of a ZP fan to go spouting his quotes all over the place. But you get the picture. Instead, I'll just go with where they went wrong in the pursuit of my money.
I'm naturally suspicious of anything that's massively popular, even more so of things that are massively popular among an unexpected audience, so the Wii hits that particular nail right on the head. However, I could easily put that aside if there was anything to make up for it.
The controls: I'm lazy. I'll happily admit that. If I'm playing a video game (at least, one that doesn't involve flailing on a plastic guitar), I want to be sitting in a chair or laying in bed chilling out. Waving my arms around like I'm swatting flies would not be conducive to the whole chilling thing.
The system itself: Graphics are a minor issue for me, God knows I still play 8-bit and earlier games and enjoy them well enough. I guess the main thing isn't so much an issue as a query. If I were to own a Wii, I'd mainly be in it for the Virtual Console. However, I don't have wireless internet and wouldn't want to pay £20 for a LAN adapter because I don't know whether their online system is accessible on my university's network - Xbox Live is, albeit with issues; PSN certainly isn't. My flatmate has a Wii but I guarantee she wouldn't let me test it even if I bought the adapter because... that's just how she is.
The games: The sheer amount of shovelware crap makes it a genuinely daunting task to find anything of quality to play on the damn thing. As it is, I don't know what games I'd get if someone were to buy me the console tomorrow. I usually state that there's "three or four" games that I want for it, but I'm beginning to suspect I made that up on the spot at some point because I don't have a clue what those games are. Super Mario Galaxy would likely be one of them, though I haven't played or even seen it - I made the mistake of buying a Gamecube just for Mario Sunshine (based on my love of Mario 64) which turned out to be dire, so I'd think twice before doing that again. I've never been a massive Zelda fan, but I'd feel obliged to get Twilight Princess just... because. Trauma Center might be fun, but the DS version almost gave me an aneurysm so maybe not. As per the thing above, I don't know if I'd be able to get Virtual Console games. The only Wii game I look at and think "yup, that'll be genuinely excellent" is Sadness, which is under a permanent question mark and being regarded as vaporware by most sources. Long story short, I don't know what I'd play on it if I had one.
The fans: ...do I really need to explain how fanboys have the effect of putting me off a product?
Having said all that, I'm probably going to end up getting one. Why? I don't know. I really don't. It's like anything that I hate for a while - I'll hate it, then go through a phase of not caring (that's where I am now) and eventually end up getting into it before getting bored and dropping it again. I know I'll end up regretting it after realising there's nothing in it for me and then leaving it unused for countless months before selling it for a ridiculously small amount just to stop it cluttering the place up, just like I did with the Gamecube, but all it'll take is a price drop and I reckon I'll be there buying one.
...blimey, that turned into a bit of a ramble, sorry.
EDIT, 12 hours later because it takes that long for my brain to work: Okami. That was probably the other game that interested me.