I don't think that's why it doesn't exist, it's more that copy/cut/paste makes sense for most things, and the cut part is bad for files, so 'grab' wouldn't be very reusable elsewhere in the OS. Or if we're being real, they just don't have it because changing Finder is a very low priority for the company.

But I agree with you that it would be a good feature for Finder! Finder is missing a lot of useful stuff, it basically hasn't changed, and when it has it isn't for the better.

While we're dreaming, a great implementation of "grab" would be to have a differently-shaped window with just a doc handle and a close button on it, and the grabbed documents jump from the Finder window to the grab window. Then you can drag and drop the doc handle, or hit the "move grabbed items" hotkey, and the grabbed files/folders would jump into the new location. Or if you close the grab window they all jump back to where they were.

Grab window floats on top of everything else in Finder, so you can't lose track of it, and if you close it the files always go home, and you can only have one at a time.