It would be a sign that Nintendo's audience includes the so-called mature audience if games like Half-Life, FEAR, and other PC FPSes had a version or a port (aaagh, more ports) on the Wii.
But at the moment it's still unlikely. Sure, UbiSoft's FPSes will probably be on the Wii but what about the other developers' games? I wouldn't be against the idea, though, even if I might not play some of them.
Now, an EXCLUSIVE Wii game that's good enough to eclipse other established franchises...that'd be something. I don't want the Wii to be the "me, too" machine.
Otherwise, in these particular cases (Half-Life, FEAR, and other FPSes, especially those that are on the PC), which pride themselves on incredible graphics, you'd be asking the so-called "hardcore" games to choose between graphics and control. And since they're usually graphic whores, how likely are they going to give up graphics for control? The Wii Remote should make the Wii the FPS King but it's not. But if some good FPSes show up, others may follow.