Nice! I hope it happens for dungeons. Less likely to have people bail if they know they can’t immediately re-queue. I wonder if you don’t get the cooldown after you’ve been in a dungeon for a certain amount of time, though? I feel like that would be fair. Or if your group fell apart. I hope you wouldn’t get penalized like that for that.
Though, legitimately, if this was an unearned instance (such as a crash) then that sucks, and you have my genuine sympathies there. If this cuts down on the number of people rage quitting out of dungeons and BGs, though, that's a win.