GPU mining was done by developers to control the difficulty. They calculated that new difficulty would be too low, so they mine as to make difficulty just half. But the problem is they do not communicate it. AND if they accept that, it means they also have to admit that they have GPU miner which they don't want to release for their selfish reasons. It is clearly undemocratic.
I don't think that the reason was that the difficult was going to be too low (it will readjusted very quickly if we mine to many blocks) , the problem was that we were generating one block every two hours, meaning that a transaction will take 12 hours to go through and at that speed, the difficulty wasn't going to readjusted until October.
Imagine the disaster if they launch minexbank in those conditions.
Cheers
MC