I think travian should do away with main building. If you see, the town hall should be the main building. Basically, the town hall is the place where the local government sits. So, the town hall is the main building of a village. Having a separate town hall and main building makes no sense.
Travian can merge functions of the town hall and main building into one building called the town center or town hall itself. Travian has done this before, they merged the 'blacksmith' and 'armory' into one building what we now call 'Smithy'.
They should also bring in the concept of the 'hospital' building from special legends servers to travian kingdoms, this is also compensate for the loss of 1 building by merging main building and town hall.