When you have no constraints (as in infinite resources, infinite space), you eventually end up with one model of an ideal factory. This changes when some things become scarce. One such thing is building space. When your terrain looks like a swiss cheese you cannot simply copy&paste a blueprint from the forum because you have to take care of the holes in the terrain.
This enables another venue for increasing the difficulty which is based in reality. Building in sandy or swampy lands has never been very easy in the real world and workarounds must be used for some things.
Another reason is that, currently, you don't need some items of the game after you have researched the better version. Such as the furnaces for ore smelting. Despite their disadvantages, such items could have lower demands on the ground you place them on. E.g. you can place a furnace on swampy lands but not an electric furnace. Or the small electric pole. Maybe fast inserters need a better foundation than their slower counterparts due to the centrifugal forces.
This could be changed for example in the following ways:
Build everything as it is now.
Only build light items such as inserters, chests, small ovens and belts but consume some cement for each item.
No assemblers or chemical factories can be placed here.
- Deep water:
Nothing can be built here, keep as is.
Maybe bridges are possible with the new rail build tool.
Build rails but consume lots of cement for support.