well it's a good a suggestion, but I'm pretty sure similar has been said.
But I don't see how this will get spammed. If a disk is an instant kill and you can throw it from far and kill lots of people if they are in a line, then what's wrong with this? This suggestion is involves close range only.
Also unlike the disk, he mentioned that this would take lots of ki.
The only thing I suggest is, you'd have to charge it up to do this. And like in the series, Trunks stroke Frieza more then once, about 3 or 4 times.