Let me suggest something that Bethesda could do if they don't implement horseriding - Let horses define whether or not you're able to fast travel. So, in order to "unlock" fast traveling, you need to buy your first horse. Obviously we, the players, would want to have full horseriding and everything that entails. But if the game isn't focused in that direction and if Bethesda feel like it won't get to where they would want it (in terms of quality), then instead of scrapping it alltogether, they could add this feature. That would mean that the horses wouldn't be ridable in the technical sense, but they would still be more than just dead weight props in the world.
Oh and on that thought, Bethesda also need to make their horses not as LAZY as in Oblivion ( http://www.flickr.com/photos/kinkseraph/5574097589/ )