Ok, im prettty drunk right now so this might not make complete sense.
Random activations… in some aspects can be pretty bad. But in other situations can be very benificial. Random activations are not completely random. Common situations are when you are at 0 frame advantage (or close to it) because of either a blocked move, something like air block, or a jump in attack (errr… i guess they are all blocked moves) and also through difficult poke strings. Activations in this case are based on probability and prediction.
Now, you may get hit out of your random activation (which is why random activations are much better when they dont have meter) or you may force them to block, or even if you are lucky get a combo. IMO, the most benificial part of random activations, is the psychological value. Lots of situations occur during a game, where if you random activate you can get a huge advantage (assuming the other person is not waiting for it)… in this respect, the actual thread of the random activation gives you an advantage, because the opponent is more cautious about sticking out a poke, or trying to punish in an ambiguous situation.
So, random activations, although the actual act of activating may not help you out, the threat of random activations helps a lot.
This is my drunken concept.