Using a prostitute is sex without having to go through the hassle of approaching women and without commitment. What's not to like?

The main reason I can think of is that there is no sense of validation in using a prostitute. Any guy can pay and have sex with a prostitute, she's available to anyone and therefore there is no sense of conquest or achievement.

For most men half the pleasure in having sex is the sense of validation derived from being attractive enough to a woman for her to have sex with you.

Is this the main reason that most men frown upon using prostitutes and look down on men who do, or is there other reasons for this mentality?