I personally thought much of "End of Evangelion" was Anno's way of giving the finger to all the fans who criticised episodes 25 & 26.
I intepreted the movie ending as Shinji choosing to accept life as it is (warts and all) and thus he rejected Third Impact. Since the whole decision was up to him, the giant Rei shattered and everything spewed out. For some obscure reason, he didn't drag the rest of humanity back with him except for Asuka (is it really her? Hmmm) and thus they all stayed as LCL fluid.
He could have created a false world but that would only be for himself (as I understood it). Everyone else would have their own little worlds and there would be utterly no interaction between real people. More people would return from the pool of LCL if they simply rejected the false little perfect worlds that Instrumentality would give them.
As for Asuka... well, I always thought that was a Asuka/Rei hybrid thingy...