I loved prime 4 despite it's flaws. But I just can't enjoy the ending

Obviously spoilers for the end of the game. Read at your own risk.

But seriously am I the only one that feels the ending was severely rushed? I get everything up to the point you enter the tower. But unless I missed something you have no explanation as to why Sylux is already there in healing pod waiting. He shows up in the beginning, and the just gets demoted to a background character causing trouble. You never actually see HIM, you never see his metroids aside from the bosses they fused to and as such they just get ignored for pretty much the whole game.

And Sylux as a endboss is just oddly disappointing. First phase was just annoying, second and third were over before it got good and then it's just over. And no explanation why he suddenly has Psychic abilities able to tear apart time and space? Just seemed.. So out of place.

The game itself was great despite some flaws. But really the ending leaves a lot to be desired in my book. Maybe I'm wrong? Did I miss anything important in the scan entries? Did I miss an explanation? If so please point it out and explain it because I just don't see it