I am nearing the end of my 4th sequential server of Travian Kindoms, and have one idea that I think could improve the game play.
By mid-game, my king's treasuries are drowning in treasures, and all the duke's treasuries were full too. There was no point in attacking other alliances to take their treasures because the limiting factor was treasury space and we knew that their treasuries would refill out of their overflow as fast as we could steal treasures. There was no way to really halt the advance in their victory points by taking treasures.
In order for treasures to be valuable and worth fighting over, they must be scarce.
After 30 days, make the robbers hideouts disappear altogether. No more new treasures at all; only fighting over the treasures that have already been released into the game in the first 30 days.
I believe that this would keep the treasures scarce enough to be worth fighting over. If you can't steal them and get them, you don't get to earn victory points. If you lose them, they cannot be replaced without risking hammers.