I’d feel much safer if a plane I were flying on had to make an emergency landing — on purpose, I do not intend to fly to either of the three countries — in Iran or Russia than in the US. Talk about a damaged reputation.
I've also been to a few other semi-totalitarian countries in the past, the most extreme of which would have been East Germany, and that was less painful to get into than the US.
But that it was simpler in East Germany says a lot.
The thing with East Germany was that they were concerned about people wanting to get out, not people coming in. So they scanned the vehicle for contraband goods going in and concealed people coming out, but apart from that it was just standard Soviet-bloc bureaucracy. The other thing was that, even though it was a somewhat totalitarian state they played by the rules, as a visitor unless you did something outrageously stupid nothing was going to happen to you. I had a camera on my lap and had been taking photos of the border installations, a border guard saw me holding the camera and said something like "you're not taking photos are you?" - "no, just changing the film" - "well, OK then".