I can say that about almost any repetitive game.
I can only play so much FPSer, or Sports Games, definitely RPGs. Because the gameplay is all very repetitive and similar. So lets not make any more games in those genres.
Heck, that also goes with 2D fighters, 2D platformers, and racing games.
The fact is some people (including myself) love lightgun games, and want to play them at home. Yes, they are usually only entertaining in short bursts, but they are still fun. And you can revisit the games easily over and over and share the experience with friends that haven't yet played the game.
Afterall, most people know how to shoot a gun, and enjoy shooting animated monsters with fake guns...its in our overly violent human nature.