I don't think mice were a mistake, but they're worse for most of the tasks I do. I'm a software engineer and I suck at art, so I just need to write, compile, and test code.
There are some things a mouse is way better for:
- drawing (well, a drawing tablet is better)
- 3d modeling
- editing photos
- first person shooters (KB works fine for OG Doom though)
- bulk file operations (a decent KB interface could work though)
But for almost everything else, I prefer a keyboard.
And while we're on a tangent, I hate WASD, why shift my fingers over from the normal home row position? It should be ESDF, which feels way more natural...