Marx's equivalent to objectification is actually called "commodity fetishism" (seriously - no pun intended). It corresponds to replacing social relations between human beings with mere exchange of commodities. In Marxian analysis, this obscures the social and exchange relations between producers and consumers, since e.g. a worker becomes utterly unaware of the people who will consume his products, except to the extent that his "labor-power" is valued as a commodity.

Of course, as Adam Smith and Friedrich Hayek observed, commodity fetishism (or the "commercial production process") is what makes modern-day specialization and complex supply chains possible: even something as humble as a cotton shirt might incorporate designs sketched out in Italy, cotton grown in Africa and plastic buttons made in China. Requiring human contact or conscious agreements between so many agents would clearly be infeasible.

The benefits of sexual objectification are far less clear, except to the extent that (as some empirical evidence bears out) some people are positive towards being objectified in a sexual context.