Apart from the obvious attempts at boosting publicity (the ME and AC armour, and the one designed by some pop star) I don't see how the costumes are any more ridiculous than anything else in previous FF games. :/
It's one thing to have a silly attire to befit a specific character, but that was simply it. They didn't dress sphere into something different, or were thrust into dressing rooms via DLC to showcase your game. Some characters had extravagant or silly costumes, but typically that was either in style for the game's premise or the character's personality to begin with. To have your main protagonist jump between (even if only optionally) prada, skimpy bikinis, or Mass Effect armor is just dumb in my opinion. It no longer gives uniqueness or charm to any character.