To correct the misconception, the GAC was not a "front of the line" card. It put you in the fastpass line. And you are right, Disney is a privilege, but Disney likes our money too. So they try to do what is necessary to keep us coming back. This is a business decision. Don't misconstrue it as anything else.
Just wanted to point out that WDW is not a "privilege" under the Americans with Disabilities Act (ADA). It is classified as a "public accommodation" under ADA, and must fully comply with ADA.
Quoting from ADA:
(7) Public accommodation. The following private entities are considered public accommodations for purposes of this subchapter, if the operations of such entities affect commerce
(I) a park, zoo, amusement park, or other place of recreation
The goal of ADA is to assure that disabled Americans can fully participate in all aspects of life, as long as "reasonable accommodations" can be made. Private companies have to go to reasonable lengths, not extraordinary lengths, to comply with ADA.
Under ADA, WDW is more than just a privilege. Disabled Americans have a right to commerce with WDW. That doesn't mean WDW is free; it only means that disabled Americans have a right to do business with WDW. WDW must accommodate these Americans, within reason.
One of the items specifically prohibited by ADA is:
a failure to make reasonable modifications in policies, practices, or procedures, when such modifications are necessary to afford such goods, services, facilities, privileges, advantages, or accommodations to individuals with disabilities, unless the entity can demonstrate that making such modifications would fundamentally alter the nature of such goods, services, facilities, privileges, advantages, or accommodations
Clearly, GAC was a reasonable modification to "policies, practices, or procedures" because WDW & DLR used it successfully for years. Disney cannot claim that GAC posed an undue burden on them. Since WDW/DLR already had a FP system in place, GAC did not "fundamentally alter the nature of such goods, services, facilities, privileges, advantages, or accommodations".
Some dislike DAS because it's not as generous as GAC. That's irrelevant. The real question is whether DAS also represents reasonable "policies, practices, or procedures". Those fighting for the return of GAC effectively are arguing that GAC was reasonable, but DAS is not. They are arguing that DAS is an insufficient accommodation for their needs.
"Reasonable" ultimately will be decided by the courts.