#1 TV-14
While I and many others have no problem with WWE being PG, many older fans who remember the attitude era wish for an edgier TV show to watch every week.
Well, AEW is going to be TV-14 so they could potentially pull away a significant amount of WWE fans due to this. It will also give them a lot more creative freedom when booking a show. If someone bleeds by accident, no big deal because it's allowed. If someone lets off a bad word, no big deal because they are TV-14.
Some of the performers could favor this approach as again they will get more creative freedom and maybe even just enjoy it more due to this.
When you put all of these reasons together, it's pretty clear WWE should start taking the threat of All Elite Wrestling seriously and try their best to counter program.