I think you're right in that, a lot of times, the difficulty was artificially inflated in those older games. Those were the days before saving games was even a thing (except in a few limited instances, and most of those instances required you to write down a complex code to save - looking at you, Mega Man), so it was sort of expected that you should be able to complete a game in one sitting of maybe a couple of hours, once you played enough to become an expert at it.

Games like Ninja Gaiden were super hard when you first started out, but the "difficulty" wasn't in the actual gameplay, it was in learning the stages, because the enemies always popped out at the same place, always moved in the same patterns, etc. So you play the level over and over until you basically have it memorized and can breeze through it with no issue.

Now that games are designed to be played for hundreds of hours in some cases, it's a little much, in my opinion, to complain about not having permadeath. It would be pretty devastating, for example, to play through a game like Final Fantasy XIII, somehow manage to get through without the party ever being wiped, and get to the final boss, only to get killed and find out that all progress you made in the last fifty hours of playing was completely gone and you have to start over from the very beginning.

I know that permadeath is an option in some games like that (Last of Us comes to mind), and that's cool that it's an option for people, but I personally wouldn't want to play any games that way.