Yes, in fact, I do oppose dual citizenship. But that is settled law in the US and not likely to change.
I know lots of Canadians who go to Mexico several times every year, and have no extra hassles. That is a specious argument.
If someone has a travel history which suggests to border officers the possibility of drug smuggling or perhaps travel to ISIS areas multiple times, do you really want them to be able to obscure that from border officers?
It's not people like you I worry about, OP, it's the bad guys. They could use the same two passport strategy to lower the risk of being caught.