Lightning's either experienced a miracle or paid for a boob job in Lightning Returns, bumping up from a Japanese C cup to a D Cup. Her breasts will also jiggle now, depending on what she's wearing, because the director wanted it that way.
According to a Famitsu interview (nabbed by DualShockers), Motomu Toriyama "wanted it bigger" with regards to Lightning's chest, a fact he found funny when interviewed on the subject. Lighting -- who Square Enix wants us to believe is a strong female character -- gets her jiggle on with various costumes in Lightning Returns, her model designer showing off how much you can make her chest bounce.
"Yes, her chest jiggles," explained Nobuhiro Goto. "Since everyone can decide what costume she’ll wear, you can make sure it does (laughs). By the way, since Lightning swings her arm when you change her weapon in the menu screen, that’s a recommended action for sure-fire jiggling! To see it even better it could be useful to equip a small shield. Look forward to it!"
Well ... okay then. It kind of undermines the whole presentation of Lightning as someone to care about when the designers are laughing about how to maximize your perving potential with her. Then again, her sole personality trait was "pink hair" anyway, so it makes a sad sort of sense.
I won't deny I always found Lightning a very attractive character, but I don't see how bigger boobs make her "hotter" in any way. She was absolutely fine as-is, and the big wobbly boob obsession this industry has is just infantile. I just hope they pay this much attention to Noctis' ballsack when XV rolls around.