No, I dont believe that anyone is trying to DE-legitimize it, because its never been legitimate. Yes, prostitution has been around for a long time...
It's literally called "the oldest profession."
but its never been an honorable way to make money, its always been looked down on because people know inherently that selling your body for money isn't good for anyone.
There's never been an honorable way to make money. We sell ourselves to others so that we can survive. There's nothing honorable about it. You're only OK with selling certain things and not others. Selling your health, youth, time, etc. is fine in your opinion, but selling sex isn't for some reason?
It's also not always been looked down on. You just have a short and narrow view of history. Check out the wiki page for the history of prostitution. It's wide and varied. In particular, Christians and Muslims have an issue with it. I'm assuming you think that your understanding is the understanding that has always been, and that it must be innately human because you must be correct. I'd recommend you reconsider that belief. Many people, now and in the past, disagree with you, and you shouldn't do things like voting with the intent to push your view on others.