Watch an ABC show like Castle. That has no "supers" in it, because it's a show about normal, regular people who are still heroes. Yet that cast and all the characters are far more engaging and charismatic than any of the actors in AOS.
The Blacklist is another show that doesn't contain any "supers". Yet James Spader has the charisma to drive the entire show by himself, and Megan Boone and Harry Lennix are no slouches either.
I wouldn't care if they didn't have any super-powered characters in AOS as long as they gave us better actors in the role, better characters and better plotting. Castle is fairly episodic but occasionally has a bigger story arc. However, it still is miles above AOS.
If they can't give us better actors (as it's a little late now), then AOS need to add someone with the charisma of James Spader to the cast who will literally infuse the entire show with his dominant personality and change the entire dynamics of both the team and the way the other actors play off this star player.