A start is better than a stop
This article from the Chicago Tribune laments the lack of legal recourse passengers have versus cruise lines. But it holds up the recent ruling on the application of the ADA to foreign cruise lines operating from US ports as a good sign. I quote:
"There's hope, though, that cruise lines will not escape important responsibilities. A recent Supreme Court decision further empowered disabled passengers regarding cruise lines. The ruling says that foreign-flagged cruise ships that sail from U.S. ports must adhere to the Americans With Disabilities Act of 1990 and be accessible to travelers with disabilities.
For some passengers, at least, it's a start."