Honestly don't understand why, if they were going to add another playable character in extra content, they didn't choose to make Red XIII playable. Their expressed rationale for not making Red XIII playable in the first place was that he joins so late in the game it wasn't worth it to fully add skills and everything to make him a playable character. Well, Yuffie doesn't join in the game at all, so why does it make sense to add episodes for her and make her playable, while Red XIII remains an NPC?