I'm not a fan of the "people can't be trusted with international law" thing. I mean, I also hate Brexit, but I hate policy laundering too. And international agreements are really good at just that, because they aren't democratically accessible. Ironically, the EU tried to solve this problem: it had a parliament with democratic elections that actually made decisions about the kinds of international treaties EU member states would adopt. However, most international law doesn't work that way. Instead, all of the sides negotiate in private and some negotiated agreement comes out the other end that local legislative bodies only get a final yay-or-nay vote on.

Fun fact: this is actually how we got the Sonny Bono Copyright Term Extension Act. This is commonly derided as the Mickey Mouse Protection Act, but the actual legislative history is that the EU had already negotiated and passed identical term lengths five years prior. They also added a reciprocality clause, granting the same term lengths in the EU to any country that also extended terms in their own jurisdiction. This is a ratchet: there's no mechanism for an American or European to object to longer terms, aside from unilateral withdrawl that will disadvantage the first-moving party. In practice, the US agreed to longer terms, because what else are they going to do? Let France or Germany have more protection for their films than the US has?

(DMCA Section 1201 happened in a similar manner, but replace the EU with the WTO. The US wouldn't pass anti-circumvention laws first, so they snuck it into TRIPS, and then used that to force the DMCA into being. The beauty of international law is that you always can find another institution to launder policy through. If there was no TRIPS, then maybe they could have bundled it into NAFTA.)

People don't like it when they object to something, and their elected representatives try and shut down their concerns. That makes them feel disenfranchised. Brexit was the inevitable result of politicians doing unpopular things and using the EU as an excuse for it. Eventually, someone was going to say "why don't we just not have international agreements"? Bonus points if you are actually one of those politicians looking to get out of, say, an upcoming tax agreement. Cause the problem (anti-democratic ratcheting), sell the solution (economic isolationism)!