The controllers are usually very limiting. Playing an FPS, for example, on a console is, to me, an exercise in frustration.

Agreed, which is why I was patient to wait for the PC port of Halo (and I'm glad I did).

On the other hand, the GameCube controller is so good for certain kinds of games that I am looking to get an interface plug that lets me connect one to my PC's USB port. (Unfortunately, the one I want seems to be sold out at all the distributors at the moment...)

No futzing about with video drivers, no wondering if your video card is good enough, no arguing with the variety of things that PCs make difficult due to their multi-purpose-ness.

And the corollary to this is development and testing being easier on consoles. You develop for a known target platform and don't have to worry about the video drivers changing or even the CPU speed or memory size changing. Bugs that might cause a PC game to crash on certain systems might go unnoticed on a console because they never cause the game to fail (regardless of which console it runs on).