Continuity mistake: In the last fight against Bane, Bane has got Robin and Batgirl by their throats against an icy wall. In a close-up of Batgirl, Batgirl's right hand is near Bane's spiked wrist guard. However, in the very next shot, her right hand is more near Bane's elbow.
Continuity mistake: At the lab, Freeze starts to laugh hysterically and raises both arms up to his face. A shot later, they're lowered at hip level.
Continuity mistake: After the cop has his keys stolen by Ivy, check the fingers on his hand leaning on the wall: they change position depending on the shot.
Continuity mistake: Ivy takes the keys from the cop and lowers her right hand. From a different angle, it's raised.
Continuity mistake: When Freeze freezes Frosty while he holds a newspaper, Frosty's position and the way the newspaper folds change between shots. The position and number of icicles around him also change drastically.
Continuity mistake: While Bane is driving the limo, after Ivy puts on the wig, the gloves on her hands disappear.
Continuity mistake: Bane is pulling Robin and Batgirl but in the next shot he's pushing them.
Chosen answer: Purely a creative decision, but based on the tone of this question I don't suppose you're honestly after an answer so much as you are just looking for someplace to express your distaste.
Phixius ★
Because Schumacher wanted to base the suits on Greek sculptures hence the nipples. Don't forget Robin's shorts or Batman wearing different colored cowls in the comics, perhaps this was a nod to that.
Rob245