It's not about taste. It's not about morals. It's not about approval ...
It's about public safety and health. People are going to engage in it, so it's an industry that requires regulation. Same deal with abortion. People are going to engage in it, so it's an industry that requires regulation.
Remember, the government is designed to serve the interests of the public. Not merely the interests of a majority. Not merely the intersts of a majority viewpoint. Government is to ensure public safety as a whole, without limiting rights.
Otherwise, if we didn't have that clarification, pure statistics would outlaw alcohol consumption overnight. In fact, that's what happened shortly after women obtained the right to vote. Ironically, it was a real case of "women know better." Unfortunately, just like prostitution and abortion, it spawned a black market when made illegal.
Again, it's hardly about taste, morals and approval. It's about public safety and health.
Of course, does that argument still hold when it comes to drug users and giving out free needles? Ahhh, now that's a more difficult one. At what point does the government subsidize personal irresponsibility? And how do you define that, because one could claim abortions are also the same argument (if you ignore the 18 years of responsibility that comes with pregnancy at least).