Having considered the big starships, what about fighter craft? They never appeared much in Star Trek, but perhaps they could play a useful role in a Star Trek MMORPG. It might be interesting if in addition to the engagement-of-maneuver kinds of fights between big ships, Star Trek Online also allows players to choose to fly smaller and much more maneuverable ships that can be operated like dogfighters.
I know a lot of people prefer that kind of fast-paced, seat-of-your-pants style of combat over the much more deliberate fight-of-attrition between two combatants with lots of subsystems that have to be taken down one by one to achieve a victory. I'm pretty sure that offering both fast and slow space combat would help Star Trek Online deliver a fun play experience that's also true to the TV shows.
The only thing I'm not sure about is whether letting players also fight in small, highly maneuverable ships imposes a significant price tag on the rest of the mechanics of space combat.
For example, we think players will get better (bigger and/or more powerful) ships as they rise in rank. But what happens to players who prefer the fast fighter craft over destroyers and cruisers? As they rise in rank, can they get more powerful fighter craft? What might those look like, and how powerful can they ever really be compared to even the smallest frigate?
Does a player who's commanded only fighters as she rose in rank to Captain get to issue orders to a Commander who's the CO of a light cruiser?
Should there be separate paths to advanced rank in the Command sequence: one for fighter pilots (up to Squadron Commander, for example) and another for line officers?
In short, is adding the capability for players to fly small, nimble ships worth the extra complexity it entails?