Nazis are back.
What kind of table do you have that you don't want a fold in the side pockets?
ANY table. Folding the cloth to the inside of the pocket changes how the ball reacts to it. Plus it is butt ugly.
It makes the pocket a bit smaller, for another.
I also like the classic look.
EDIT: And stretching the cloth so there is no fold turns the side pool pocket into a snooker pocket. That is the worst of all "solutions."