As someone who works at the MK, I do have some thoughts on the issue. I completely understand the issues involved with persons with truly legitimate medical problems (loss of limbs, autism, etc...) as it can be exceedingly difficult to negotiate a WDW vacation taking those medical issues into account. I would recommend an ECV to those with issues regarding standing/walking. It will let you go through an alternate entrance (if available at said attraction) and in general make your day much easier for you. As a side note here, I truly dislike having ECV's in the park for a two reasons.. first, too many people using them just don't have enough experience driving them. Secondly, they go too fast...period. They should not be able to go any faster than an average human walks, but they do. This has caused so many close calls to guests both in their own party and others that I'm surprised there haven't been more lawsuits over this issue yet but I can see that coming in the future as more and more people are renting them. I also hope that GAC cards, or something else they come up with, will continue to provide needed assistance to some of our guests. That said, I do think they need to seriously rethink/revamp the whole program as it is taken advantage of much too often. Almost everyday we have guests come up with GAC's and expect to get directly onto the attraction. We do the explanation of what they are for and the restrictions involved and they still go away disgruntled as if we're not doing enough for them. It actually angers me that they not only are trying to take advantage of the truly nice service available, but then they turn around and treat CM's such as myself as if we are not providing them the Disney magic they wanted.
In the end, the current situation isn't really fair to those who truly need assistance, and to those of us trying to provide assistance and a little Disney magic to everyone.