From what I read online, this is apparently only implemented in the Enhanced Editions and not in the originals.

Have you tested it yourself?

(Simple way to test: Create a fighter/druid, cheat yourself some full plate mail, and then try to equip it.)

Min/maxing and power gaming has been around long before either of those games. It's almost as old as D&D itself.

Druid/Cleric restrictions only apply to weapons. Jaheira can wear full plate armor.

Then we are talking about different things or I explained myself poorly. In classic RPGs, we improve/Level up our characters so we can progress in the story. In Diablo 2, we improve our character in the sake of being better. Better loot, level up... this is the main goal of the game. Why do people kill Diablo or Baal repeatedly even tho they are the end Bosses? To get better gear. You finished the game and you still keep playing just to level up. In classic RPGs, once you finish the game, you no longer feel the need to improve your character.

2nd Edition was just not balanced to start with. It was from before the days when balance was really a thing, and the system was far less mechanical than 3rd/4th especially, with far less explicitly in the rules.

So translating wooly tabletop rules with no sense of balance to a set of hard and fast rules a computer can do is always going to be a bit flaky balance wise.

Unless they've changed it in the Enhanced Edition, fighter/druids are not bound by the druid's armour restrictions, only by the weapon restrictions. This is correct implementation of the AD&D 2E rules (at least the rules from the core books).