I have voted with you, as unlikely as it is to ever be granted, but you are, I hope, aware of the ability in LightWorks to size masks separately from the size of the underlying pattern?
I've attached a rudimentary grime exercise where a drawn grime pattern rests on a texturemap at a separate size.
A mere shadow of what you ask for, but a big step toward more surface variety.
Dwight Atkinson