I pretty much always felt that Noctis would always be the only playable character. As for making the gameplay more casual friendly with one button interface, that has been part of the series course since 94 so I don't see why people are whining about FF being made to cater to the lowest common denominator of player because they have always done that since VI.

I'm hoping combat will have a bit more variety but I always expected this game to play like KH with Noctis as the only playable character and the rest of the cast would be A.I. it's an Action-RPG, they have always had you controlling one character with A.I. partners since the days of Tales of Phantasia, Star Ocean 1, and Secret of Mana on the SNES. KH games have never allowed you to use the partner characters in battle so why would you think that Versus XIII would be any different?