Right, I think they are wonderful complimentary systems, as Nintendo has probably the most consistently great first-party devs in the business and I can't imagine missing out on SMG1/2, DKCR, Sin and Punishment, etc. Some of my favorite games of the whole generation are only found on the Wii.
but on the flip side, if I was Nintendo only, I'd been way late to the party on Mass Effect, The Last of Us, The Walking Dead, Portal 2, Uncharted 2, Arkham Asylum. Never experienced some of the best multiplayer experiences I've ever had with Team Fortress 2, Street Fighter 4(lol 3DS version), Gears of War 3, Left 4 Dead 1/2, Halo 3. All those brilliant smaller titles like Pac-Man Championship Edition, Outland, Splosion Man, Geometry Wars Retro Evolved, Bionic Commando Rearmed, Journey, Mark of the Ninja. Can't imagine missing out on Bayonetta, Crack in Time, Rayman Origins that wasn't in a gorgeous 1080p...
call me greedy, but I love video games too much(and have way too much spare time) to limit myself to just one console. I want the full spectrum. Nintendo's included, but they're only a small but essential part of it, in the grand scheme of things.