Endless Legend had a cool system called "Capacities". Each units would have around 5 - 10 traits, making their use unique. ( A full list of capacities here ) , my sugestion is a adaptation of this system for endless space 2 


            Adapting this feature to endless space 2 could have a lot of upsides; the endless series game design have always prioritize unique factions. Even if you were playing the same game, every new faction felt like a completely new game strategy. "Capacities" made each one of the 46 units unique, offering a lot of choices between units, that helped each fight being more unique, and more fun. The same benefit could be said about heroes. Right now some heroes like e and π share way too many similarities. Capacities would make each unit, and game, more different.  

              How Capacities could be best put on the game is still up to debate. Unlike endless legend, endless space don't have unique ships for each race. One idea could be the 10 population bonus be a "Faction Crew Module" for ships. Giving a special faction capacities for your ship.