Start with something from Cataclysm (keep first two expansions for Classic), scaled to lv60 with meaningful item level loot.
You stumbled over the root of problem without realizing it, and I believe it's similar to my "
interesting times" theory:
The old game developers at Blizzard have been replaced by fresh out of college kids, easily swayed by the Blizzard reputation to work for little money. But they are hungry to make a career and a reputation for themselves. They want to be the next rock stars. So they have all those "great" ideas for the game and want to implement them.
They don't want to readjust the loot, especially the items those boomer developers created a decade ago, which aren't even at the company anymore. Since then the overall gearing, stats and item strategy has changed multiple times, so you would have to "reinvent" all those items to make them meaningful and not break things.
And even if the old developers were still around, they wouldn't want to touch those old items, either. Because players have fond memories about them, especially those old school set bonuses and tier sets. Those changed the way how classes played, and that doesn't fit the borrowed power system of the month.
This is not "an easy win", but if they invested time and resources into it, then it would show a lot of goodwill to the players. It would also be the first time in a long time that they would acknowledge in some way that they remember the roots of the franchise--even if that is what the fans crave. And that would be a really hard and sour pill to swallow for them.
EDIT: missing words, I am tired