Rotating Blocks by Sneak/Crouch Input

I've seen a couple ideas for rotating blocks and wanted to throw my hat into the ring.

Using the sneak/crouch option to rotate blocks is a simple, effective, and streamlined way of learning the new mechanic, utilizing it, and implementing it into gameplay. Sneak/crouch already allows us to place blocks/items on interactable blocks or objects without interacting with the object/block instead. 

I figure it'd work like this: Hold Sneak/Crouch, hold the Place Block button, as long as both inputs are still held use the mouse/joystick to rotate the block being placed at 90 degree increments along 2 axes. I'd refer to it as "holding" a block while you're holding both inputs.

This would be useful for decorating and designing architecture, structures, statues, 3D models in other senses, etc. Also great for fixing the block facing certain direction depending on orientation and view of the player thing. 

I've seen Mojang post a little disclaimer against vertical slabs and I'm not sure why, hoping its more of a crafting thing rather than a rotating thing. 

Any advice comment below!