> The mouse is not a "clumsy" input and there are plenty of situations in which the mouse allows more efficient usage than the keyboard like when navigating through 2D space. For example it is clearly more efficient to place your cursor at a certain arbitrary point in the document using the mouse than to navigate there using keyboard commands.

Have you ever used emacs? If not theres a mode called ace-jump, which I'm pretty sure beats every interaction with a mouse to get to a certain point within a document. I'd wager that, if we'd start at the same time, I'd be at that point before you actually touch the mouse with the hand that you just lifted. Honestly, it's worth checking out. There is a lot of things that emacs and vim are brilliant at, they had tens of years to figure things out after all...