Rewarding and logical building progression
This makes it so minor settlement buildings provide +1/2/3 building slots per tier, as is in warhammer 3, the same is true for major settlements.
The scaling or resources generated by buildings is also more logical and dynamic, being +20/40 for tier 1/2 for example. Making building buildings more rewarding.
I did this because empire building feels terrible in pharao, with little to no reward for making investments in upgrading or developing your settlements. A pretty major oversight by the developers imo.