Nope, not going to happen. Can you imagine the addtl costs involved??? Do you really want to pay those addtl costs? I don't.
In all reality, there just aren't that many ECVs using the buses at any one time. And that 20 mins addtl time, loading and unloading? Wrong. The 'on foot' guests get off that bus, long before the ECV is unloaded. So, your time may have an addtl 5-10 mins, depending on how many ECVs are loaded, the skill of the operator and the bus driver, doing the loading.
Everyone seems to think that there are many more ECVs now. Well, while I have noticed more ECV use, I don't think it's out of control. Why? Those that use ECVs, tend to find that it is very inconvenient to board the buses. It adds a lot more time to their bus ride than it does to ours!!
In all reality?? Each bus carries two, and some buses can accomodate three, ECVs. I have seldom seen a bus with two on it...and that's at least one trip a year, and usually more like two!!!
BUT....I have more of an issue with strollers. Someone already mentioned that it's annoying for guests to leave the stroller as is, right up until the time to board the bus. I have seen guests try to board the bus, with the child still in the stroller. And then, they commenced to arguing with the driver...'well, the baby is sleeping and I don't want to wake her up!!'. The driver was less than sympathetic. And if someone put a folded up stroller on a seat? You can believe that I would be the person requesting that they remove the stroller if there were guests standing!!! Seats are for human behinds, not for strollers!!!
If you leave your resort within 45 mins of park opening (from 8:15 to 9:30ish), you are going to have a ton of company. It's best to get the earliest bus you can make. Much better to be standing at the park, waiting for rope drop than to be among the hordes arriving for 9am!!!