hate to be misquoted as I never used the term "worthless" but semantics aside, your original post was aimed at hotels that would split a $100 night from $90-room/$10-service to $10-room/$90-service and this, I assume, is due to the lack of points derived on the service charges..........

well, at some hotels they add tourist taxes, city taxes, state taxes as well as Fed taxes and as I recall charged me a registration fee in Russia to boot.......
in some countries there are no taxes added........all shapes and sizes...........and none of these add-ons accrue points.........

so, some hotels charge 5%, others 10% and still others 15%, but we're still not at, or even marginally close to 90% example given anywhere in the world........

your question of who decides, (legitimate question) well IMO several factors are taken into consideration, but since I'm not Marriott, but special counsel for another brand of over 70-properties, I can't and won't address that question - perhaps Socrates will........

BTW, don't props get reimbursed by MR's for award stays based upon a certain formula (based upon occupancy & brand) up to and including rack rates.........if so, then I doubt the hotels will be switching to your $10/$90 senerio unless they also obtain service charges too......