To my knowledge, they've never really updated the endeavor list.
Difficult ones are a pain but not bad, per se. But there are some that are disruptive. I'm thinking of Dewan Arthropods and Gorn making it hard to actually run missions on Nimbus III - I'd maybe remove the 120 Arthropods tier from that at least, and expand Gorn to include non-Nimbus mobs.
I'd also add in more variety on the TFO objectives. We only get Borg, Iconian, Lukari and Competitive. It would be nice to have some of the other groups in rotation for variety. Likewise more enemy factions on the hit list.
It might also be fun to have a top tier option to complete a mission from a certain arc that doesn't get replayed much.