Actually I thought the person w/ disability made valid statements, so I'm not sure who was referred to (unless OT comments were edited).
Speaking only for myself, I DON'T reserve handicapped rooms (since I'm not) nor would I.
I've only been 'upgraded' once to one at arrival (and I'm assuming the hotel had no reservation for that room). Only dif in that case (can't remember hotel or chain) was a dif toilet & tub/shower.
Would I book a room for disabled if it was $100 cheaper? No. Much as I'd be tempted, I am totally not willing to take something away from someone who will need it.
And yes we can say Hilton wouldn't offer it if it wasn't available, but what if someone logged on after us & truly needed the room & it wasn't available because I took it?
Everyone has their own ethics line; that's one of mine. YMMV.
Cheers.