Different Village Sizes

Make it so Villagers come in multiple different sizes. Maybe choose between 3 different sizes, or have a size value between 0 and 1 that determines characteristics of the village. As all villages are procedurally generated, a lower value would mean it is more likely to stop generating it, or the size value is highest at the centre and sort of tapers out

Smaller/less advanced villages might not have libraries below a certain value, or not have blacksmiths. Farms might not have wooden barriers, instead being dug into the ground like they are in savanna villages.

Higher size/civilisation levels might be more likely to use stone bricks as materials for buildings. Desert villages with high size value/civilisation level could be based around an Oasis at the centre. (The Oasis would actually just be generated the same as other village centres)

The highest levels might have protective walls around the centre, or possibly even Guard Villagers.

This kind of mechanic has near endless possibilities whilst staying mostly seamless with the existing game.