Re: OP. Yeah, pretty ridiculous. Americans who travel very much (admittedly a minority) also cringe at the thought of yet more reciprocal measures directed at Americans.

GUM airport actually has a lot of the worst of both worlds: Most American procedures and hassles, but not really America (you'll have to do it all over again if continuing to the mainland). Not only that, but they make even transit passengers go through immigration (including U.S. citizens). Imagine if every international hub airport started doing that!

Seems like an Air Canada could see an opportunity and try to capitalize by incorporating it into marketing ("Try Toronto instead! Fewer hassles!") Maybe even do like SQ or BI and allow free stopovers for nationalities that can easily get a Canadian visa.