It's not the world that's changed, it's you. Objectively that kind of trip is a lot safer today than in those days (although the specifics may differ; Afghanistan and Iran are doubtless more dangerous for a westerner today than in the seventies, but Eastern Europe and a lot of SEA are now safer).
Yes generally thats true, but you just mentioned a massive bottleneck that all the folks doing some variant of silk road (Europe to say India) are facing - Iran and Pakistan.
I've visited Iran in cca 2017 for mostly hiking up highest active volcano in euroasia (Mont Damavand) and spent some remaining days in places like Isfahan and Yazd, and it was one of best travelling experiences ever. People unspoiled by mass tourism are a very rare experience these days, very friendly folks, everybody spoke english very well and seemed highly educated, you have ancient history all around you. These days, I wouldn't go there (to not be used in some political chess game, common people didn't change obviously).
Pakistan is more free, but more dangerous too and as a tourist you stick out massively.
There are other changes for the worse - most of Africa is massively more dangerous than say in 50s and 60s. There were famous folks who rode some basic old cars from say Egypt to South Africa and had just great mostly positive adventures, these days such a trip would be pretty much suicidal as per their own accords.
Yeah. I’d be very cautious about the Middle East and some other specific locations including a lot of Africa. But I’d have very few concerns about Eastern Europe with obvious exceptions.
