My take is: If there are no regular rooms, just accessible rooms showing up, it means the place is nearly booked, and what they have is accessible rooms available.

If you put a note in your reservation, they'll likely move you to a regular room if they have one available, and if they don't have one available, you're as entitled to the accessible room as anyone, on a first come first served basis.

I agree, the showers are less than ideal for non-challenged folks in terms of only having a small bump preventing water to get into the rest of the bathroom, but that's a minor issue, IMHO.