What about it? Maybe it'd be a good idea to make them upgradeable like houses? Early settlements could not afford large construction projects and early temples and palaces were quite small and not very lavish. They were upgraded later by rulers who were able to accumulate wealth - making them bigger and more beautiful. Such upgrades should be expensive (carried only by succesful rulers and during times of prosperity) but they could give players satisfaction and maybe some prestige among other rulers/nearby settlements.
Hebrew Bible mentions upgrading both palace and temple by rulers and while it took place in iron age it can also be applied to bronze age too.