Ask HN: what if the patent system was decentralized?

The typical example in favor of patents is that of drug discovery: it's expensive to conduct but a drug is trivial to copy once approved. Since the FDA is the govt entity mandating the trials (which is a substantial portion of the time and cost), why not let the FDA itself grant exclusive approvals to drugs for n years? E.g. approve only Lipitor (Pfizer's brand) for 7 years, and then approve Atorvastatin (the chemical).

Other regulated industries could do the same: the regulatory body offers the temporary monopoly to incentivize innovation. Are there any unregulated industries where patents are critical to innovation?