In the end games sell on the Wii platform, the kinds of games matters.. 'big games'... semantics is a bi*** so I'll look at it this way:
Roughly half of the Wii's sold to date are online; this example is a bit tanjent but the point is that when and not if but when the install base reaches the point of 100 million+ while the combined install base for the PS360 is just kicking 60 million's door down it's going to be hard to ignore that install base.
I'm not saying 'big games' are going to be coming to the platform at that point, I am saying that the types of games that do sell will be the 'big games' for that platform.
Should a Resident Evil 5 appear on the Wii platform, I assure you that it would be a failure speaking in the long term, the game won't sell like a Wii Sports or a Mario Kart, and seeing as how the consumer base of the Wii has expressed that they will purchase a game 12 million times and counting, anything short would be a perspective failure.
However should a Resident Evil 5 Wii appear on the Wii platform then I can assure you it will not be the Resident Evil 4/1 that anyone expects, and so it would be recognized, shunned and loved all at the same time.
Going back to my tangent point; Eventually if that ratio keeps up of roughly half the Wii owners being online. (Which it should since users being online is influenced by content and content so far has only increased with time.) The ammount of people online with the Wii could rival an entire platforms install base for either PS3 or Xbox360. Meaning their could be more reason to work on a kind of game that could use this.
MMORPG players didn't come around because an MMORPG was there, MMORPG's came around because people were on the internet.