That is pretty much how I see it, too. With the Wii the backwards compatibility (read: rebuying of old stuff) is a key element of it's selling point. The PS3 has it as more of like, a supplemental feature.
Besides I'm sure it varies WILDLY from game to game, anyhow.
Actually, the VC (virtual console) is no more than a supplemental feature, too. It's not nearly advertised to the same extent as the controller and the Wii-specific titles. Add to that fact that you're going to be spending $5, bare minimum, to get a VC title and the fact that the internet is crawling with sites that offer emulators and ROM's (though, technically, not legitimate unless you own a hard copy of the game, but we'll discard that for the obvious reasons that few people actually appear to care about legitimacy when using an emulator, heh), and I don't really see how the VC is a big selling point for the Wii. Lastly, throw in the fact that the VC really doesn't have a huge variety of titles yet, and you can arrive at the conclusion that buying a Wii for its VC is just about as senseless as buying a PS3 to play your library of PS2 titles. My opinion - not fact (as is the case with most points in these threads).
I agree, though, that the backwards compatibility of the PS3 (which, essentially, is either just playing old stuff that your PS2 could, or buying more PS2 games in a market that [hopefully] will begin to favor the PS3 - gotta move the old titles after the PS2 is in the cellar, after all) is not something to work one's self in knots about. It would be a bit of a stretch to to try and justify the PS3 as something that one would buy JUST to have the ability to stick in old games. It should be a feature that works in a satisfactory manner regardless of whether or not it is in the spotlight, though.