Yeah, when we picked our 4th gen RAV4 - rear seats not sliding was a bummer, as you can stuff more cargo in there if the seats could move up. But given all the other improvements, we didn't see it as a deal breaker. Being able to open up the hatch vertically comes in real handy in some instances. Same thing with no "remote" seat folding capability - I can fold the seats on my 3rd gen via the two lever latches near the rear door. With the 4th gen - have to go around and physically use the levers on the chairs themselves.
I move the seats sometinmes when I load all kinds of building materials at the back of my 4.3 But most people will have no use for it.
Maybe those with pets would like to give them more space in the cargo area?