This is by design. The goal is to get people stuck in Microsoft's crap store where they get a fat 30% cut of all software sales by trickery. That's why you had the Surface Pro...the flag ship product that could do it all and actually filled a niche. And then there's the Surface RT, the turd no one could love if they knew its dark secret...but its a Surface and it was cheap so whoops I bought it because I got confused like I was supposed to be.
But the word is out RT means abomination now. So its time to go with the even more ambiguous Surface nothing to muddy up the waters even more. Coming next year expect the RT version 3 to be re-branded as "Surface Pro E" or maybe they'll go for the full power bait and switch and just call it Surface Pro 3.0. This last change would have come eventually though, the obvious end game to shoe-horning their app store into existence is to close the door on any software sales they don't get a cut of.
I think the opposite sort of happened though. RT actually ruined the whole Surface brand rather than the Pro artificially elevating it. Probably a lot of people (ok, probably not that many people) bought the RT under the mistaken assumption it could do things only the Pro could and then returned it to the store before washing their hands of Surface tablets altogether. Here's the part where Microsoft screwed up, they forgot its a lot easier for a customer to return a tablet to a store than it is for OEMs or customers to return Windows 8 operating system software.