Cars made back then were easy to fix in a sense, but broke often, got terrible gas mileage, and were largely death traps in any crash over ~45mph. There are certainly parts of modern cars that should be easier to fix yourself, but in a lot of ways they're less difficult to repair.

The engine compartments are smaller, and the engines have more parts which means it takes longer. However if you can hook up and read the OBD2 system codes you get a lot of diagnostic info that was never previously available. This can mean you send a lot less time redoing work. The real limiting factor is space. If you're not averse to Quora, there's a nice discussion here https://www.quora.com/Why-are-modern-vehicles-so-difficult-t....