Glaring issues that were NOT addressed in 2.1

[waka_swag]

WoW manages this just fine, by showing something like [+10% to hit level X enemies, +9% to hit level Y enemies].

But I feel like something like that would only work against trash mobs that have generic base level stats. Against bosses, with different stats as far as their strengths, and resistances it would be far less useful to just give you a specific percentage against X level enemies.

I really don't understand why this is such a pressing issue but I'm not a min/max type player considering this game doesn't even require it for any reason, so seeing clear increases means nothing to me considering even if you have the absolute bis gear, you're still gonna be able to get the job done just the same as the person with slightly modified gear. Is it because WoW shows it?