Neither 1E or 2E was at all playable; too much arbitrary rubbish in both. If I *HAD* to go back to a 70ies or 80ies game system I'd probably go to Runequest and very heavily house rule it; I'd more likely make a system of my own cobbling together bits from Runequest, Rolemaster and D&D.
Love or hate new editions game mechanics have come a long way in 30 years.
This is awesomely out-there Bob. We played 2E for 10 years, and played plenty of games with "more modern" mechanics than it at the same time, and we never had any particular problem with it, so "at all playable"? Uhhhh, it actually was very playable.
We had more of problem with 3E's playbility than 2E, frankly, given that things like the difficulty of designing monsters according to the system genuinely impaired my ability to write adventures, that 3E's obsession with AoOs forced us to think a lot harder and more boringly in combat, and that 3E's PrCs, LAs and multiclassing in general allowed "clearly within the rules" munchkinism on what I would say was a literally unprecedented level for D&D as well as forcing people to pre-plan their characters in a way 2E never had.
So the idea that, in RPGs, "progress" is always an improvement, I'm afraid that's wrong. 3E had a lot of things to offer, but it sure wasn't a straight "gameplay upgrade" from 2E. Nor is 4E a straight "gameplay upgrade" from 3E. It fixes many problems, and introduces a lot of issues and wrinkles of it's own. It's very playable, but then, D&D/AD&D always was.
You need to clearly separate the ideas of having "neat and clean" rules, which thrill some people, and being "playable", because they're quite distinct things. SLA Industries' rules are a lot cleaner and neater than 2E AD&D's, yet I don't think many people would say SLA Industries was "more playable". Quite the contrary.