As for inventive human beings, I would say it's quite the contrary more often, because they are driven by the puzzle, not the prize. External incentives are actually pretty bad at fostering innovative thought. They provide tunnel vision, which is great for getting someone to rotate a lug over and over all day, but bad for getting someone to engage in anything requiring lateral thinking.
As long as there's paedophiles they'll be child porn
As long as there's peadophiles they'll be peadophiles who need an outlet. The details of that outlet could change. For example, if there were robots that make suitable sexual partners for humans, the majority of pedophiles would probably stay within that safe territory, especially since children often have bad hygiene and are so tempermental.
Firstly they exist for technologies which could be made secret, but would benefit society more if they were made open.
But no informed, self-interested inventor is going to volunteer such information if the benefit for themselves is better as a trade secret. That's the point I'm making. Patents do nothing to interfere with trade secrets. There is the possibility of 'guilds' arising and keeping everything black box, but that does nothing to prevent independent engineering or reverse engineering. If you are afraid of trade secrets, then push to reduce the protections of trade secret law, and limit the terms of NDAs.