My first D&D was the Basic box set with the Erol Otus artwork on a red cover, purchased by saving up money from mowing the lawn and my allowance (I'm thinking Basic, 9th printing). I loved it IMMENSELY. We played a few games of it and I was hooked enough to get AD&D (or 1E for you young people who think Star Wars was always called Episode IV). I played AD&D from 1982 to 1992 or so, alternating as DM and player, depending.
We stopped because many of the things that we found delightful in 1E eventually became onerous. All those subsystems that were initially intriguing and diverse became just tedious. All those cool powers, items, tables and spells eventually became a burden to manage and navigate. It was nice to be able to add things willy-nilly, but it also felt like it lacked cohesion across its systems. ('Why yes, the Jester is a viable class right along with the main characters; heck, he's better than a bard!") It could be punishing and unfair, which is fine if you want that, but eventually we didn't. 1E, as someone noted above, rewards awesomeness. But the reverse of that is that if you don't roll up an awesome character, you don't want it: people either rerolled characters or were forced to compromise, invent new systems to compensate for the dice (the 4d6 method, point-buy, XP bonuses and so on) or moved to other games when having to constantly address various issues became something you didn't want to keep doing. 2E meant to address many of these things, but all the AD&D players I know felt alienated and...wait for it...BLUE. Some folks were fine with the change, but that was the jumping off point for everyone I knew.
We switched to GURPS because that system (which had its own issues) made every character feel like they were a hero at whatever they'd chosen to do, something that 1E didn't do unless you survived long enough to make it to a level where you felt competent. We didn't return to D&D until 3E, which brought many of us back to RPGs after a long absence. 5E felt like a nice return to some of the feel of both 1E and 3E, particularly its simplicity, but with 3E's more uniform approach. Some folks like 1E's harshness in the same way that some folks enjoy the Dark Souls video games and that's great. But for my friends and I, the systems have lots of inconsistencies and gaps that modern systems address better and thus are what we want to play now.