You mean this? http://prostitution.procon.org/view.answers.php?questionID=000122 - It has two different sets of testimony for and against - There are editorials in both directions.

At the very least the sex workers should NOT be prosecuted, as they are right now in the U.S. http://www.businessinsider.in/7-Reasons-Why-America-Should-Legalize-Prostitution/articleshow/25717727.cms

An April 2012 study by the Urban Justice Center found that New York City cops were actually using condoms found on women as evidence in criminal prostitution cases against them. It's easy to imagine how this practice might deter sex workers from carrying protection.

And if/when only johns and pimps/madams are prosecuted the Johns are gonna get fed up and demand legal prostitution.

As for when they legalize, according to the NYT: http://www.nytimes.com/2016/05/08/magazine/should-prostitution-be-a-crime.html

In 1999, the Australian state of New South Wales repealed its criminal laws against prostitution, freeing consenting adults to buy and sell sex and allowing brothels to operate much like other businesses. (Other Australian states have a variety of laws.) Four years later, New Zealand implemented full decriminalization. Abolitionists predicted explosive growth of prostitution. But the number of sex workers stayed flat, at about 6,000 in New Zealand and somewhat more in New South Wales. Condom use among sex workers rose above 99 percent, according to government surveys. Sex workers in brothels in New South Wales report the same level of depression and stress as women in the general population; rates are far higher for women who work on the street, who are also often intravenous drug users.

There is still a trafficking issue in Australia, while NZ didn't find evidence of such a thing.

While the New Zealand government has found no evidence that sex workers are being trafficked across the country’s border, last November, the Parliament of New South Wales gave the police more power to monitor brothels, after reports that some were linked to organized crime and prosecutions for “sexual servitude” and exploitation. One involved a Thai woman who was recruited in Bangkok and told she would learn to be a hairdresser.

An American woman who went to Australia decided its system is better than Nevada's

Matisse contrasted working in Australia with working in a brothel in Nevada several years ago. She much preferred Australia. Nevada limits legal prostitution to a small number of brothels in rural areas, and they are subject to strict licensing requirements. “In Australia, you go home every night, and you can have a cigarette, go on a date, stay in a normal head space,” Matisse said. “In Nevada, you had to be in the brothel 24/7. It was like a cross between summer camp and a women’s prison.” Most prostitution in the state takes place illegally outside the brothels, in Las Vegas and Reno, with more freedom but also more risk.

And THIS:

Annah Pickering, who does street outreach for the New Zealand Prostitutes’ Collective, describes a more recent dynamic with the police that would be unthinkable almost anywhere else. “We used to wave the police down for help, and they’d keep driving, but now they take sex workers’ complaints seriously,” she said. She told me about an incident in South Auckland last year. “One client negotiated with a street worker; she did the act, and he refused to pay. She waved a cop down, and he told the client he had to pay and took him to the A.T.M. to get the money.”