It was a necessary evil that Euclid needed to prove some things which he wanted to be true in his geometry. We can assume Euclid disliked this postulate because he avoided using it. Many of his proofs in Elements would be easier if he had used the paralled postulate, but instead it is used rarely. Many of Euclid's contemporaries in Ancient Greece also tried to prove the parallel postulate with the other four, showing that it was widely disliked and considered "less pure" than the others. Here is a source to go further.