I thought that the Uni Power was dependent on it's wielder. As is, I don't buy it being as powerful as the Void currently. But let's say that Susan Storm had it, or the someone of notable power, I would agree totally with you. The Uni power is a boost, and it's current wielder is what exactly? A resurrected base level human? Perhaps the Starbrand could take him.
Unfortunately it's one of those things that varies in depiction. Even relatively low level characters have had pretty significant showings with it, yet with no clear explanation as to the level of the amp. So yes, in essence it does fluctuate from user to user but the results are quite similar. Whoever inherits the power is most certainly not someone to be trifled with. Continuing in that fashion, the current Captain Universe is held in pretty high regard. As carver said, she likened herself to the universe itself. It gives some indication.
I agree, however, until I see something other than her proclamation to great power, I'm forced to take it with a grain of salt. Now if I see her shrugging off blasts from the predations of the Phoenix, then, and only then will I be flabbergasted.
I always thought that the uni power grants the user the power to complete that task it has chosen that individual for. Which is the reason for so many different power showings.
I can understand that. Totally. On the other hand however, my mind wanders to other cosmic abstracts/forces such as Eternity and the like. We don't need to see him fart a galaxy into existence to know that well...he commands that level of power. We take it as is. But hey, that can probably be attributed to the many misfiring synapses in my muddled excuse for a brain.