This is typical. Usually cars high up the ladder like this don't have rear fold down seats. It would be nice as an added feature. I'm sure people at Acura have thought about it and didn't include it for a good reason.
From what I've known in the past Acura's especially their higher end line up of vehicles never had this feature but just a slot from the center armrest that opened for Skis. Acura thought it through that the people that do buy their vehicles wont be lugging around a lot of luggage.
I believe that Krell may have influenced the decision as they really load up the back ledge with speakers. Also you don't have the split "to spoil the beauty of the back seats"; in addition it helps to improve the structural rigidity, etc. My wife wanted the split seats, but I have decided it is worth it to take the time to rent a van on the rare times it is needed.
I would rather have a recline feature with cooled seats compared to fold down rear seats for the RLX. Very limited space with the hybrid battery pack behind the seat. Instead of the upper part moving back, the seat cushion could move towards the front seats and slightly up at an angle with the front part of the seat bottom. That would slide down down the seat back at an angle for a more comfy recline.