But this is where the law and it's application applies. The law isn't that Disney only provide one form that a customer MUST accept - It's the inverse, the company must accept a reasonable accommodation.
Example: if I need to test and have supplies for my Type II diabetes, Disney can't say "we have first aid centers, you must use those - you can not bring in your own needles or food" if the guest is simply requesting to be able to carry their supplies in bring in necessary supplements.... because a court can rule the request is reasonable. Disney can provide an alternative, but they must consider reasonable accommodations.
Same way that Disney really can't dictate the only accommodation is use a wheelchair. For instance, they should allow sitting canes, or other mechanisms too.. and they do.
And "but isn't fun" isn't a binary thing... I think everyone can acknowledge without much fuss how much burden an ECV is, and Disney wouldn't have a ton of success arguing a customer should take on that burden and financial burden as a sole alternative if the guest really didn't need it. Reasonable alternatives will be easy to argue for.
It would be a dream... it's one of those things that you don't notice at first unless you're looking.. and this push for space and other reasons to eliminate them has been a real determinant to me visiting. You see sitting walls are much more common in a lot of the newer landscape designs.. but they only go so far.
Just look around the hub or most walkways... it feels like a death march when your back is failing you and you can't find anywhere to sit.