Would she have remained a human then? It seemed like he didn't really love her and still had another girl on his mind. I'm sure he liked her as a friend, but any kiss looked like it would have been a spur of the moment impulsive thing because he was 'in the mood' and not out of love.
shareThe problem is, the story would have ended too early. Ariel would have gotten her voice back, told him who she was, and they would have lived happily ever after, and Ursula would have still been a menace.
The problem is, Ursula had never intended for Ariel to be able to fulfill her end of the bargain, she needed Ariel as leverage against Triton later. So she sabotaged the kiss with her eels. In fact, Ursula even commented after that that Ariel was better at seducing the prince than she thought!