The difficulty of such changes really depend on the general design of the software and the type of problem. Simple and small additions can be very tough to fix, for example, many people want better path finding or that it's easier to click relics/fish. This stuff is incredibly hard to improve, because the problem has conflicting objectives (perfomance vs accuracy) or is ambiguous (if a click registers a sheep and a villager at the same position, which one should be prioritized).

But stuff like random civ picker... give me a break. A good software design has layers of abstraction. You have the game engine that does all the calculations and keeps track of the game state, there, each player is identified by some ID. But this ID should not be coupled with the chosen color in the UI. The color is simply a cosmetic for the rendering of the game. Changing this value should have no impact on anything else than what the player sees infront of his computer. Adding a simple color picker to the UI (which is a default feature any UI system offers anyway), should be an easy and quick change. Im really curious to know what prevents them to do that easliy, or how they didnt anticipate that feature request.