I would expect most vim users to feel the same since those complaints are either considered features or the common barrier to entry that vim has anyway. Am I wrong?
I have ack.vim installed, but I frequently open the project in TextMate to search with TM's AckMate bundle. Project search one of the last things with Vim that I haven't had a good solution to.
ack.vim works, but it blocks vim so you can't do anything while it's working, and also the quickfix window is not ideal for a lot of uses.
Example: "set grepprg=git\ grep\ -n"
:nmap <C-f> :!ack <cword><CR>
The benefit is one of UI/UX, it doesn't actually perform an action you couldn't perform text-only.
A few notes:
"Button" label should say search or go.
There is no "results not found"
It is hard to tell if it is doing anything, maybe add a animated icon showing it is working.
The functionality you mention exists for Emacs.
There are others, but this should suit anybody's needs.
Edited to provide examples.