WOW! I've now just discovered this lively debate and read through all 6 pages. Firstly, I must be missing something because I don't think I've ever seen an accessible room available for booking at a lower rate whenever I've done a search (or maybe I have and simply discounted it after reading the description)
Personally, I would probably never book an accessible room, but I don't blame anyone who would, given a full $100 a night inducement. The fact that the price is so much lower tells me that the hotel is very confident that the room will go unfilled unless an economic incentive is provided to the general public to fill it. The corollary to this is that the hotel is also very confident that the room won't actually be needed. In the case that it is, the ONLY right thing to do is to give it up to someone who actually needs it.