Why do we wear superman t-shirts? or buy baseball cards? or buy action figures? because we admire a hero and we want to add something of that hero to ourselves: strenght, beauty, pride, honor, you name it.
She likes the Little Mermaid, a symbol of independence, of coming to age, of music and beauty and wants something to value to herself, and i think she succeeded.
But, if you are a horny old man, you´ll only see her tummy, which I agree is perfect.