Even if your invention isn't easily reverse engineered, it could still be re-engineered by others once you've demonstrated the concept and the market. Trade secrets aren't guarantees.

Right but that's my point. I don't think there is clear evidence that it encourages innovation, and if the technology can be re-engineered from the end result then you are not really helping society with a patent system. If it cannot be re-engineered from the end product, I don't see a reason anyone would use the patent system.

Gotcha, but I guess the counter would be that you can't really know what someone else will be able to figure out. Some groundbreaking historical discoveries were made in quick succession by multiple people working independently; others weren't.

I think the system was not designed so much for end products, but for industrial technology that produced end products.