You know what's not fun? Mining. Having to click on a rock, click on mine every 4 seconds or so is pretty boring.
You know what would be less boring? Being able to to that once to mine a rock down to nothing! This is my vision.
Let's conjure up some details: essentially, all this would do would be to restart the progress bar immediately after it fills. Each fill of the bar would have the effect of a single mine action has now; you receive chunks from the rock you're mining, any bonuses gained from others helping you mine is received, a check for bonus goodies is performed and recieved if applicable, the size of the rock is depleted, and you lose energy. Hitting the cancel button would do the same thing it does now: simply stops mining.
This is definitely not intended to continue botting the same rock once it regenerates, if you're still hanging around. Once the instance of the rock you've begun to mine depletes completely, the effect ends.
So, what are the benefits? Mostly, just not having to click "Mine" every four seconds. Why is that a good thing? Well, you could, say, participate more actively in chat. Or go do a pee. For the powergamers, it also means less time wasted on your Earthshakers.
Mostly, it's about not having to click mine every 4 seconds.