The main difference between HW and EW is that HW has content that's more repeatable, even though they have less content in general. PotD had quite a lot of rewards tied to it, people would repeatedly do that just for the varied items they get from the sacks. As for Diadem, trash it all you want, yes it was bad, but it also was repeatable, the emergency missions giving RNG loot means people have the option to repeat it if they want the shiny BiS weapon.

We're missing optional, repeatable grind in EW. It's not just that the formula is stale, it's that they gave us the bare minimum of engagement using the same formula, so some people would feel inclined to blame the formula.