My group is still on a modded AD&D 2e Player's Option because the WotC-editions were too crude for our style of playing. The main issues were the combat system dropping speed factor and thus the combat phase, which led to combatants apparently queueing up and then performing all their actions only when it's their turn; the botched adaption of the magic system in which a perceived 50% of all spells were suddenly transmutations; and the complete lack of compatibility between editions. While I can convert 1e modules on the fly, I would have had to "re-imagine" hundreds of NPCs and creatures under the new rules. Drizzt Do'Urden and Minsc can tell a story about how well that usually goes.
That said, I wholeheartedly agree that standard 2e still suffered from many tabletop strategy game rules relics and a strong bias to keep player characters small. The original rules were also from before computer games and various film franchises changed gamers' ideas about how a fantasy world works, so they reflect a much more medieval world, somewhere between Lord of the Rings, Prince Valiant and Monty Python's Holy Grail. TSR emphasised that you shouldn't be able to just walk into a store and buy a magic sword, because that would ruin the mystery. In a way, the Forgotten Realms were already a departure from that strict code, because they painted a different picture. To me, it was only a question of balance. If the heroes can wear five magic rings at once, so can the villains.
One of the first adaptions I made, was ditching old style saving throws. While they're actually based on a formula not so different from 3e, I agree that they weren't easy to comprehend because TSR kept that formula a secret and only published tables. And then - as with many concepts in 2e - you had the rules on page 17, the corresponding table on page 60 and further information in a different book you still had to buy. For playing 2e material with 3e saves, the categories still give me the DC, so to speak. If I remember correctly, the limitations to ability scores and many other stats are due to the game only going from -40 to +40, but I couldn't find a source for that. That's also why they decided to insert the exceptional strength block for fighters. This made sure they remained within human numerical limits, but still had the muscle for heroic feats, like thieves could climb even completely smooth walls. Thus, weapon mastery, extra strength and hit points are the boon of the fighter class, since they're undergoing more physical training than clerics, wizards and rogues. Spending less time in the library and more time in the gym would mean multi-classing.
In the end it all depends on how you want your campaign to work and feel. To me, it's more a collaborative effort to tell a story with the players, while Gary Gygax allegedly got mad at Rob Kuntz when he defeated his masterpiece dungeon, the Temple of Elemental Evil, which probably explains where that anti-player bias in the TSR-editions came from. The rules should serve the game and the players, not vice versa. It would really be interesting to see a computer game hybrid D&D that combines the strengths of each edition. I have surely taken my notes from BG3 and 5e for use in my 2ePO games.
