When D&D exploded into my middle-school world I had no comprehension of the history of the game. I searched desperately at bookstores for copies of the DMG and MM, to no luck. I do faintly recall a bookstore in Tucson AZ that had some unrecognizable D&Dish books, but they weren't the droids I was looking for. In hindsight I think they were Judges Guild products, but it was so long ago I can't be sure.
It took some time for me to get the core books, though I did get a few Dragon issues early on (the mighty #83 being the first, and still my favorite, if only for nostalgia's sake).
It was only later that I discovered that the PHB was really intended to be the gateway drug for AD&D. And it was one of the last of the hardcover books that I acquired back then!
TSR always seemed embarrassed about the original D&D. What I mean is they were constantly trying to make new RPG systems to get away from it. Classic D&D seemed to be the neglected orphan as the company went on to AD&D and AD&D 2nd edition getting further and further away from the elegance of the original game that was such a huge hit.
For a short time I was enamored with GURPS. Looking back now I don't understand why TSR didn't take the original D&D and adapt it to other genres to become the first true universal RPG. Instead they made various RPG's that bore little resemblance to their breadwinner. Boothill, Gamma World, Star Frontiers, Top Secret, Marvel Super Heroes, and the infamous Indiana Jones RPG and so on.
I'm all for innovation, but when you have the best and best selling RPG in the world, why in the world do you do everything in your power to run away from it? Why weren't these game designed to be fully compatible with the original D&D? There was obviously more going on at TSR than good creative direction. What a sad state of affairs to end up being bought out by an usurper like WotC! All because you don't "get" your #1 product.
When I look out at the OSR landscape I am blow away and inspired by the creativity and passion for this beloved game. But, I see a little bit of the short sightedness that blinded TSR. Why are so many trying to copy, to duplicate -literally- the original edition, when there are so many frontiers left to be discovered that the original edition can be adapted to?