Aizen did not give the Espada their powers, he augmented them by turning them into arrancar. Gremmy creates powers by thought, including the entirety of Gwanael's being, hence why he can use them if he imagined it. Also what Gremmy created wasn't a simple vacuum. He opened a void in space and if you noticed, he had nearly shut the void. Zaraki cut through space to open the void back up. Don't worry, I'm not suggesting that Zaraki is on some Hulk level stuff. But that's beside the point. In short it is completely different from what Aizen did. To say the guy that all the other Stern Ritter fear could be "crushed" by a guy who had to sacrifice his life to essentially draw with one of said Stern Ritter makes no sense to me at all. Back to Enel, he is inconsistent I'll admit, but most prominent characters have some inconsistency. Madara getting tagged by weak Obito for example.