Something has always nagged me about empire building in games, basically it is that as the ruler how is it that i am directing building in multiple city across a continent in a pre-electronic communication age. This is especially true for elemental since the idea is that you are your sovereign.

My basic idea is that as the sovereign you can only issue build order instantly in the city you are in (or close by in the country side). For other towns you must have messengers take you build orders or other directions to the city. Expanding quickly then becomes complicated due to the time lag to get orders out to the far away cities.

Aside from messengers you could also assign champions to run a city for you. This bring up some interesting mechanics in the type of people you assign to cities and what they will do. Is it really a good idea to let that wandering bard you just recruited run one of you newly foundered border towns?

As the game progresses you can research new magic techniques and building to allow for faster communication between towns or for when you are leading an army in the field. Eventual even instant communication.

Another  intresting things this could also lead to is problems with cities you have in enemy territory, with no way to get messengers there you cant really direct them.

Just an idea to slow down the early game and maybe focus more attention on the capital city growth.