Ethics are only one component: there's also the simply criteria of whether the policy meets the desired goal. If an anti-rape law somehow resulted in more rape, having an ethical argument about it would be absurd.

The stated goal of patents is not a moral imperative to protect inventors, but rather an economic hack that is meant to incentivize invention for the benefit of society, only benefitting inventors as a side effect. The fact that it is achieving the opposite of its goal means that an ethical discussion is worth having, but mostly irrelevant (see also: the Drug War).