General "/plot floor" Command.

I agree. For those saying that it defeats the point of W/E, you should understand that WorldEdit was originally built for fine editing, like spheres, percentage composition placement (like in Van's screenshot) and more complex structures. This is literally just for the floor of the plot. The only real editing you can do is change the block used. It does not work vertically or horizontally above the plot floor.

This could maybe benefit Elites too. They won't have to jump to the plot corners to place their edit points and use //set.

I'm voting +1.
 
Theres not much of a reason for this command due to the fact that Elite players already have this option with World Edit, I understand that it might be fun for default players not being able to edit their plot like they want, but you can always ask a Elite or Elite+, if one says no, you can always ask another nicer one. Hope this helps! <3