As you say everything is based on interpretation. Disney is contracted to pick up all luggage that is tagged with their tags and if that is the case, than any statements made after the contract are superfluous.
Besides if you plan to ride a Yak to MCO you better figure out how to get your bags aboard a plane arriving MCO without you on board.
Okay, but the sake of 'discussion', let's agree that the regular, run of the mill person has no idea, nor do they care, about what the contract that Disney has with OIA says. They will be told, by Disney if they ask, that yes, they are supposed to ride the DME bus, and then their bags will be delivered to their resort room. I know...I've made the call on several different occasions, pretending to be Joe Shmoe, WDW guest. If you call Disney directly, and ask them if you can send your tagged bags with DME but you take a towncar (for instance), they will tell you that you are expected to ride the bus in order to have your luggage delivered. That, and only that, is my point.
I don't think there will EVER be a time when ALL yellow tags are not whisked to the sorting facility and on to the resorts. There is just too much volume. However, what I think WILL eventually happen is a guest that does not ride the bus, the bags will be held at Bell Services/Luggage Services. When the guest calls wondering where their bags are, they will be informed that there is a $$ charge for transporting their bags since they did not ride the DME bus and it will be charged to their room. Then their bags will be delivered to their room.
Also on the flip side, it appears from posts I've read here that there are so many folks claiming their own bags that it's becoming a problem on the buses, so when folks arrive at the DME welcome center with their bags, they will need to turn them in there to be transported on the trucks, OR pay a fee to carry bags on the buses above normal carryons.
I have to agree with you. At some point, who knows when, Disney could very well decide to charge extra for luggage delivery. If you do not board the bus, your bags will be delivered to the resort, but there will be a small fee attached to it's being delivered to your room. Not a big deal.
As for those numerous bags being brought to the bus at MCO, oh yeah, there sure are. I realize that waiting an addtl 5-8 mins is not a huge deal. But, when you're sitting on a bus, while 10 bags are disbursed from under the bus, well, you get nudgy. You want to get to your resort and start your vacation. It's annoying to have to sit there, while those who brought their bags with them, have to get their bags, and then, hopefully, hand over a tip to the driver. I wish they would charge a per bag fee for that also.
None of these issues are huge ones. I don't believe there are that many people who are tagging their bags and hoping into towncars. But, I have noticed more and more people bringing their bags to the bus with them, rather than wait for delivery to the resort. Deal breakers? No, just an annoyance for those guests, like me, who want to get started on their vacation.