Can't really argue with everything you've said, Roan; because its all true.
Though, what has really baffled me over the years is specifically why most developers and core gamers alike have both moved away from the Wii. I have never been able to put my finger on it.
Why have most core gamers come to dislike the Wii? Because there is not many games for them. But then, you have to wonder, why did developers choose to not produce as many core games on the Wii as they have the PS3 and 360? It doesn't matter what demographic Nintendo is marketing the system to (which can be argued to be everybody, but lets pretend that the core gamers and casuals are on different levels), it is up to the developers to create great games for the system. Games define the system, not the other way around.
It is like some sort of chain reaction. The developers don't develop good core games for the Wii, and as a result, core gamers go elsewhere. And it isn't like core gamers were never interested, in fact, they were excited. When the Wii was launched, I recall you being very excited for it, but look now, you probably haven't touched in in months. Wonder why.
As you mentioned though, this casual aura that the Wii has built upon itself, for whatever reason will likely never be broken. Which is saddening, because to me, it is the most interesting and exciting console, conceptually, on the market at this point.