Its the culture and philosophy at ironclad that produces some of the greatest designs but also is its limiting factor.
No one will tell you rebellion performs much better than diplomacy because the peformance game is mediocre and they crammed shadows and more lighting to take advantage of the headroom.
The to do list:
MP IMPROVEMENTS, MULTI-CORE CORE SUPPORT, ANOTHER EXPANSION, DLC PACK, GAME UPDATES, SINS 2 & SINS TOURNAMENT..
This is just an example of what Ironclad has to choose from. My guess is they are going for the quickest and most cost effect solutions first or have small teams tackling all the areas.