I will often write things such as "I don't really need a hearing accessible room" or "Upgrade request for exec floor, 1 king or 2 queens ok". Because I'll generally book the cheapest room but not care about bed type, and on those occasions I book an "accessible" room because it's cheaper than a regular room, I'll note that I don't need it so they can give it to someone who does.

Whether or not the hotel actually reads the comments - no idea. I suspect it varies from property to property and employee to employee.