FWIW, I think "It's Only a Paper Moon" showed us that having episodes where actors who were previously only guest stars carrying the entire show would work very well.
I think "Half a Life" proved that years earlier. And a lot of DS9 episodes were built largely around supporting characters -- Garak, Rom, Nog, Leeta, Bareil, Winn, Dukat, etc. Heck, they even did an episode revolving around Morn, though he was technically hardly in it. DS9 ended up with a huge ensemble cast in which the Starfleet characters often played a secondary role.
Personally I'd like to see more of the Federation beyond Starfleet. Too often they're treated as equivalent. Sure, ST should be largely about space exploration, but aren't there any civilian explorers?