I wish they'd do a little more with Risa in general, horseback riding would fit well there. There should at least be some mini games to do there or something, right now it's just a nice place to sit and enjoy the scenery.
Captain Picard loved his horse riding, even had his own saddle. Kirk loved his horse riding, had his own stable and horses. Horses by these two captains were a common trait. I haven't seen any horses on any planets. I'm not sure how you'd incorporate this, but I think it would be great to have Captain Picard's saddle. And I think it'd be great to have a horse in-game. A pet that follows you? An option to ride a horse? I'm not sure how it would be setup. But somehow, you have to bring horses into the game.