The problem isn't so much the lack of a buyback feature as it is the laggyness of the UI. Whichever dev at SE thought having an almost entirely serverside UI needs to be reassigned (preferably to a department that doesn't directly affect the game).

If the UI is fixed, the buyback feature is much less necessary. While I wouldn't object to having it, I don't really feel that it's necessary once the UI itself is fixed.