There should be party control switching with L2/R2 or accesible via Party menu. That way we can play as other characters, try out new magics, and other things. And Sora/Riku/Kairi or Sora/Riku/Mickey should get their own version of trinity limit.
Most of us use these "cheats" to make gameplay more interesting, like battling 3 bosses at the same time, or giving Sora a different moveset. "Cheating" is only wrong if it is used to do something like make Sora level 99 unless you already beat the game.