Let me elaborate more.
Lets say you are wanting to build a small town for a map. A builder might be making a pretty good size town, so they will want to save on build time. I'm also taking a guess that the connecting faces of two blocks are not removed on individual blocks(yet). So the bigger the chunk of per block, the more optimized your buildings will be.
Since most doors are 3x width blocks. If you want symmetry with your house, you pretty much are forced to have some sort of 3 block path going from your door to whatever for consistency. You can't for example, get a panel floor without some hiding of that last 4th row in some form or another. This also limits your ability to utilize panels as a fast and efficient way to establish a full floor, as well as being able to use some of their unique textures.