hong said:For consistency's sake more than anything. Big things tend to be strong; most monsters in the MM that are size L or bigger have 20 Str or thereabouts. There's nothing stopping you from making up a big monster that's weak, but that would be an unusual creature.
I understand that big things tend to be strong. I guess I justed figured that saying something would get a negative strength if shrunk is a poor way of saying big things should be strong.