Not sure I agree, although I do understand where you are coming from.
I agree the equation is not as simple as 20% less ROF equals 20% less paint shot (which is why I said roughly equals in my posting where I first mentioned this). But I'm certain you will see less paint being shot.
Most players, particularly those in the lower ranks, shoot not so much because they have a target, but rather because they can. As soon as somebody starts shooting back at them, they tuck in and stop shooting, until they get a chance to come back at and start firing again.
If anything, lowering the ROF will increase people's opportunity to "break the deadlock" of an opponent pinning you down, as there is less paint coming your way, so your argument of people shooting longer ropes, I think, is very flawed.
You seem to argue your point mostly from a point of view that would equal that of the better players, the people in the CPL and such. Now while I fully agree that most of these guys are well capable of adjusting their game to whatever set of rules gets imposed on them, most of the lower divisions, which is where the money really comes from, can not. They will move just as much/little as they always have, shoot for the same amount of time, so paint consumption will go down.
And given the fact that the top leagues get a lot of their paint, and the lower leagues have to pay for theirs, I doubt the industry will be happy. Even if you are right, try convincing THEM of that... If indeed the avarage back player has gone from 14 pots to half that (once again, I think you are right for the top leagues, where a true back guy seems to be extinct, while in the lower regions we still see Fatty McFat-a-lot with his gut full of pots), there should already be a marked decrease in paint usage. I doubt the suppliers will back anything that even reaks of selling less paint in that case.
Fact is, the bigwigs don't give a flying f*ck how much paint is shot by the pros, or if they do, the less the better, as they are paying for it. They DO care about the amount of paint shot by the people that have to pay for their paint.