Culture modifies human natural behaviour in all sorts of surprising ways. You cannot tell out of hand which behaviours are natural (whatever that means) and which are cultural. Why are women's appearances scrutinized to much greater extent than men? Is it because our culture* discourages male objectification, or because it encourages female objectification?

Even if it is natural, that doesn't mean it's desireable. That's just an appeal to nature.

While laws are an extreme method, they're routinely used to better ourselves, and even more often to better others. It's worked for (what we currently consider) undesireable behaviours like theft, smoking in public places, environmental pollution, seatbelt wearing, illegal parking, murder, and looking funny at cops. That's a pretty varied list, so why wouldn't it work for sexual objectification? I don't think we should use such a drastic approach, but it's not ridiculous, either.

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* Cowardly assuming we're all in the West.