In D2 finding gear felt fun. Runes were rare but powerful and sets/legendaries offered different build paths. You also had control over magic find with the ability to lower your power to increase magic find.
D3 (much later) expanded sets so that a number of builds were viable per class, making it fun to find any piece of gear. They also added rifts to challenge yourself to no end. The devs liked watching people push higher tiers and celebrated it.
D4 does not have runes or sets. Every legendary effect can to removed from the legendary and added to any yellow piece of gear. As a result, you’re typically chasing random yellow items for a .1% increase that all feels very samey until you find a unique. Currently, uniques are not even close to all being viable. Also blizz activity monitors unique drop rates and decreases them/bans people for finding ways to increase drop rates. The devs do not like people pushing harder stuff because that means they spending less time looking at the intentionally shitty (free) transmogs. They want you to grind away for days to get incremental success so you tire of your looks and buy skins and battle passes. If that explanation sucks, then I have no fucking idea what they’re doing. Maybe they expect us to grind because they don’t know how to create more content?