Communism has to emerge out of pre-existing social conditions. There is no point fantasising about a revolution that’s going to abolish families, for example.
Western societies are not necessarily all socially liberal, but that is the predominant culture. For centuries now, people have become progressively more tolerant. A majority of the non-boomer population at least have a strong “live and let live” attitude towards religion, drug use, sexual preference, immigration, sex work, etc. And Boomers are more tolerant than their parents generation too.
Some Western communists seem to have a disturbing enthusiasm for enforcing what they see as a good or moral lifestyle on other people. Ignoring any theoretical pragmatic necessities, the aim of a communist society is to guarantee freedom from economic exploitation, rather than impose additional moralities. And anyway, it seems an obvious strategic failure to go against the current of the time, and associate communism with social conservatism. Most social conservatives are going to be inherently anti-communist because communism is a poor vehicle for realising the kind of society they want.
Obviously personal freedoms are a secondary concern to ending exploitation and imperialism. However, it may not seem that way to liberals. Associating communism with social conservatism makes it anathema to the liberal portion of society and no more attractive to the conservative side. It is a complete own goal.
I don’t think sex tourism is necessarily the major component, at least not always. Certainly not in Vietnam where every town, most of which Westerners never go to, have brothels. There is also a big trade in sex trafficking in China for example, where poor Vietnamese women (usually children) will be sold to rich Chinese men. Western sex tourism is a relatively small aspect of the wider problem.
I guess my basic assumption in regard to sex work and drug use is that they are going to happen regardless of attempts to prohibit them, there is plenty of evidence for that, and so they need to be controlled and afforded the best protections possible, which is only possible through legalisation. It’s about harm minimisation rather than perfection.