@ We can quite easily just replace the tile under a house when you build it, its not very hard (To allow for deformation). We can also not have blocks appearances by creating loads of different modular tiles (Once you have a few assets this is very easy)
In terms of control, you are of course right, we can never achieve complete control with tiles as we would with landscapes, but with many tiles we can still make it quite possible to make anything.
And in the navmesh department, I believe there is an update at runtime bool that you can turn on for a navmesh.
All in all, I think that the pros way outweigh the cons, but that’s just me 