It should have started in the asylum (spoilers)

... with the characters convinced that they were delusional (Dr. Ellie Staple explaining away the events of the previous two films) / having had their abilities sapped by "the machine". Then the initial fight and capture of David Dunn and The Horde could be shown in flashbacks to reveal to the audience how they got there.

Seeing them display their powers with a big fight and THEN becomes quickly convinced that they were "normal" didn't work at all.

Also, there should have been a few more "cured" superhuman patients, just to make the asylum less boring.

I thought this film was interesting but the whole "secret society" storyline was very poorly integrated.