Sadly what is sufficient one year may not be sufficient the next... its the problem with a vague law like the ADA. At one time you merely had to have a ramp, then someone thought that it should be a tiered ramp of only a specific angle or less... making it more difficult to understand is that these things also seem to be a state by state interpretation. But if the wheel chair access to Beauty and the Beast show is any indication of what is required now, the Monorail platform would fail because the BatB has the tiered ramps that have level rest areas every so many feet. I've pushed a wheel chair up both and the platform at the monorail seem much steeper than the BatB ramps.
The biggest issue you raised is what is "accessible" and what does it mean. The law doesn't define it well enough for anyone to really know, so various jurisdictions try to write laws that they think meet that requirement and then various people file lawsuits and courts randomly give more and more definition to the word... but I don't think it can or ever will be truly settled as to what "accessible" really means.