Protecting inventors is one path toward innovation, but it should be a byproduct of maximizing innovation and not the end state.
If the objective of the patent system is to foster innovation, then it should grant patents only if they are necessary for innovation, i.e., innovation wouldn't reasonably occur otherwise.
Amazon's one-click patent versus drug patents are two good cases. If the patent system didn't exist, is it reasonable to think someone else would come up with a one-click method of shopping? Yes. Drugs, however, often require hundreds of millions of dollars in upfront investment. It is reasonable to think that pharma companies couldn't raise the necessary capital, and therefore invent these drugs, without some protection.