Also, I'm okay with the Pre-TOS period being filled with incidents we've never heard about it. Just because the characters don't mention it doesn't mean something hasn't happened. One thing I'd like to see in the future is some more interactions with abandoned plot races. Xindi, Tandarans (who appear to be a Federation-level species), and Suliban.
Personally, I'd love for some humans to not entirely be happy with an unprovoked mass murder of its citizens. Also, the Tandarans not being Federation founding members but a race that is still vital to securing the Quadrant's position.