So, is your suggestion just to be able to rotate the block while it is placed? If so, stairs could become applicable with this also.

 

Well there may be difference in how this works.
Paintings are changed as it is just the texture that changes every time it is placed, there's no specific angle that it needs to be placed.
Stairs and Terracotta, however, must be placed from a certain standpoint to change the rotation of the texture. This means, that the server would have to rotate the block itself, which I am not sure is entirely possible.

This is entirely speculation but I do think it's educated nonetheless.

 

In a way. Paintings are entities, but glazed terracotta (I assume you mean glazed terracotta because the former Hardened Clay - now called terracotta - doesn't cause such issues when placing it) is a block. I have no idea how this would affect switcher performance, but I can imagine a few issues with rapidly modifying blocks via a command/ability.

 

Can't edit the world in an async manner due to minecraft restrictions. Realistically, if CraftBook adds it, we can consider it, otherwise we have more important manners.

 

+1 if its possible :D