One issue they have is that nothing really feels important. In WWE people have all sorts of goals like winning a rumble, money in the bank, main-eventing wrestlemania, etc. Creating some decent annual traditions and even tastefully revising history to make things seem more important would help. They could lean into the indies, RoH, and Japan for help with that.
Another thing is that they don't create many stars. It's more like a fed full of mid-carders. MJF is the only guy they've really built up from nothing, but they've got space for more. They should pick one face to get the Cena/Roman mega-push treatment. And another heel to be the monster who chews through wrestlers in a year long title-run. Could also give this guy a Carder-esque streak of beating unbeaten at a certain PPV.
Basically AEW doesn't feel like a place people grow in. It's a place where established people collect a check and indie guys are happy to be in a major fed even if they're doing nothing. If there's no sense of accomplishment and disappointment, it's hard to actually care about the matches and stories.