This is for situations for when you could really use a second hand to move objects around. Besides, is it really that much harder to move your hand off a mouse than it is a keyboard?

Also, I have been practicing, and it's really not that hard to operate 2 different mice with the same hand. Although, using a mouse wheel with your pinky is bit of a bitch.

There is times I don't need my 2nd hand for the keyboard tho....

If you have a gaming mouse, you could program the extra buttons on it for the keyboard functions. making it the one mouse to rule them all. =) Personally i don't have one yet. I've always used a regular mouse i modified to make it fit my giant hands. (added metal) I just finally ordered a R.A.T. 7 so i hope to be able to do this when i get the game.

my album with pictures of my giant hand and tiny ghetto rigged mouse.
http://imgur.com/a/X4aRk

Those are old pictures of it before i added all the rubber to it. just bare metal.

I use a Razer Naga for just that purpose. The only time I need to use the keyboard in-game is to "talk".