For ennemies AI, ok: we made progress. But for human-vs-human gameplays, we basically had everything in the nineties.
Warcraft II over Kali (to simulate a LAN over the Internet for Warcraft II didn't have battle.net) was basically the gameplay of Warcraft III reforged. Half-Life and then it's counterstrike mod were basically the FPS of today.
Diablo II (development for Windows 1995 started in 1997 and game came out in 2000, so not 2000 per se but nearly) was basically so perfect from a collaborative gameplay point of view and was the perfect "hack n slash" game.
It was so perfect that a few weeks ago Blizzard released the exact same game, with an identical gameplay, even down to most bugs (some were fixed, like the eth armor upgrade bug). It's the same game, but with modern looking graphics.
Games were so good that more than two decades later you can re-release the exact same gameplay with updated graphics.
That's how perfect things already were.
So very hard disagree that "games had simpler gameplay".
Many game genre back then had already reached perfection from the gameplay point the view.
Since then we added shiny.