Each existing race does in it own way have some unique characteristics (Caitian pounce attack, Vulcan nerve pinch, etc) when a character is made.
It was always kind of crazy to me that the powers that be tried something that "split" development strength in two when they were stuggling with game content as it was, by having two separate factions with completely separate content.
The easiest way to 'double' the existing content - and make the possibliity of future factions a reality - is to port all existing content for generic use by ANY faction, just as the Featured Episodes work.
It would be a fairly simple thing to make all Fed content playable by Klingon players by simply having any combat against klingons a "House" diasagreement/conflict. Something that only requires text changes - again just like FEs.
Klingon content playable by Feds would entail a sort of 'espionage' storyline to get behind enemy lines (which could be taken at K-7 without actually having to cross into Klingon space). Again, simple changes to mission dialog boxes would be just about all that is required.
Sure, this is a 'cheap fix' to the problem, but with very limited man-power and little to no future mission development for the game as decread by the guys in charge, it is the ONLY solution left - and the only hope that another faction will EVER see the light of day.
So, while I can empathize with your desire to make races more diverse in a "One and a half" faction game by boosting abilities, the real solution is to make enough content available so that MANY true different factions can start at level 1 and be able to level all the way to cap using it.
Minor Factions would also be a great way to diversify with very little effort.
For example instead of starting as a Starfleet officer at ESD you could join the Vulcan Science academy (Bajoran Militia/Orion Syndicate/Gorn Hegemony/Ferengi Alliance/Fed Merchant Fleet/Andorian or Caitian Military) when starting a new toon.
Vulcan Minor Faction (Vulcan Science Academy)
Fed-Alligned, Science career only
unlocks for 4.000 c-points
starts on Vulcan at lvl 25, short starting quest line, rest the same as normal Fed Quests,
- D`Kyr Science Vessel (unlocks @40)
- D`Kyr Science Vessel (T3-Version, unlocks @30)
- Vahklas Class Ship (starting vessel)
- Vulcan uniform options for Boffs and Player character
- Special Equipment Vendor (Vulcan weapons for Space & Ground)
- VS prefix instead of USS
all it would need would be a starting/commerce hub on Vulcan, similar to what we recieved for Bajor, new Uniform options and a single new ship.