Hi,
As it happens, my finger memory seems to have ctrl-a ingrained for ending isearch, although I suspect that at times I would also use (or try to use) ctrl-b, f, e, p, and n or maybe even an actual arrow key.
Speaking for myself, I rarely want to edit an isearch field. Again, that's probably due to 15 years of emacs habits where isearch fields couldn't be edited even if I had wanted to. But the upshot is that I really miss the ability to end the isearch by moving the cursor.
As a non emacs-refugee I actually find the current behavior more intuitive -- as in, I'd expect to be able to edit the search term (and happy that ctrl-a/e hop around in there while I'm playing with it) while in incremental search mode.
Just my 2 cents, -steve