One of biggest endgame problem Anthem have right - 100% vertical progression.
Problem with that is killing over 99% of older content. It takes about 50 hours maximum to get to endgame, even for the ppl who not rushing it at all. And once you reach it - you won't use any newer epic gear, and eventually stop using those at all. Where they are still in loot table.
The endgame loot really should aim much more to the horizontal progression (aka variety within the same power-level), rather than keep trying getting more and more powerful gear.
Now i hate bringing examples from other games, but right now i can't really think of the better way to explain how to do it better, than telling how it was already done much better in another game.
I am talking about Path of Exile, and it's endgame loot-grinding. They really nailed it perfectly, where even though game have huge variety of unique items (would-be equivalent of Anthem's masterwork/legendary), but good endgame builds still utilize high variety of rare (equivalent of Anthem's epic) items.
How was it done, you might ask (if you haven't played PoE yourself)?
Well, PoE unique items, just like Anthem MW/L gear have unique effects, that only that particular piece of gear can bring. But other bonuses are pre-set, and not always perfectly fit for your build.
Where rare items can have really huge variety of bonuses and those bonuses variables.
So how to translate it to Anthem:
1)Make epic gear scales up to same level as MW/L gear. Damage for weapons, and most importantly defence attributes on components. Don't bottleneck-it to usage of MW/L only for endgame.
2)Make all MW/L gear have preset inscriptions with pre-set variables. And try not to put huge numbers into those. Unique effect MW/L gives alone would already make ppl want to use those, so no need to make them even more powerful.
Just those two steps would already insure that ppl still will want to use several MW/L gear for their builds. But would seek to amplify those but "grinding" good epic gear with good inscriptions.
P.S. There is of course much more than just that can be done to improve players' endgame experience: Player market. More controllable crafting with semi-guaranty outcomes. Diverting loot table to different parts of gameplay, and many more. But those first steps certainly will be a very good start on optimizing the endgame.