Hot take: Chica looks weird without her beak and not at all sexy. In case it wasn't obvious, she's a chicken. Well, an animatronic with chicken characteristics like a beak, orange feet, and she's yellow like a chick. And I know why her beak is removed when she's moving around the pizzeria in FNAF 2. It was originally an error that the developer kept in because it made her look creepier. And he's right, it is creepier because Chica without her beak is the equivalent of a human with their lips torn off. Makes for an effective horror monster, but not so much a sexy character.
I can understand the logic behind your reasoning, especially if your reason for thinking the animatronics are hot is their animal characteristics. Basically the same reason why a lot of furries find anthropomorphic animal characters attractive. Personally, though, I've never been able to find female characters with beaks attractive, so Toy Chica with the beak never really sold for me. The beakless version, on the other hand, with the sharp teeth and small white eyes in the dark void, always multiplied her attractiveness times 100 for me; finding a way to blend in the creepy aspects of her appearance but still make her sexy. I respect your opinion, though.