Justice and Rule
Legend
I greatly prefer the more specific effects of the various levels of exhaustion over a boring blanket numerical pentalty. For much the same reason that I prefer magic items that have unique effects over generic +X magic items, and the same reason I prefer gaining new abilities on level up over simply increasing HP and proficiency bonus. Numbers are the least interesting part of an RPG to me, so any mechanic that is expressed solely through a numerical modifier is inherently less interesting to me than one that is expressed through exceptions-based rules. Furthermore, I think the harshness of the exhaustion penalties was a feature, not a bug. There’s value in having status conditions with real teeth, as that gives them more power to create strong gameplay incentives. Classic exhaustion is one of very few things other than straight-up character death that could meaningfully threaten PCs of any level in 5e.
I feel like there has to be a middle ground between evocative but too mechanically harsh to be used often, while easier mechanically while lacking flavor.