The good news is that it brings at least part of the trade within the law. The people involved in a legitimate exchange of services have recourse to the law; huge step in the right direction.

Will there be illegitimate activity? Yes. The good news is that resources now spent chasing "no harm no foul" types of cases can be re-directed to deal with activity that causes real harm.

As to the "moral" dimension: I believe Christ did not exclude prostitutes from the congregation; should we then exclude them from society and the protection they deserve as citizens?