Whether looking at the proposed changes from either a macro level or a micro level, Disney World has always promoted itself as a place that supports family togetherness. If due to a disability(ies), Disney insists upon splitting up families as an accommodation in order to allow disabled people to enjoy attractions, Disney World will no longer be seen as a place that supports families with disabled family members. According to an ADA training manual:
"The ADA says people with disabilities are entitled to “the full and equal enjoyment of the goods, services, facilities, privileges, advantages, or accommodations” that a public accommodation provides to its customers. In other words, every type of good or service a business provides to customers is covered by the ADA. All businesses that serve the public must provide equal opportunity for customers with disabilities."
Asking disabled people to wait away from their families in order to ride is not full and equal enjoyment. Others who are able bodied might choose to participate in rider switch but Disney is basically telling a portion of the disabled community that it's rider switch or nothing.