Agreed that the defense has either been ignored or some really piss poor front office decisions via the draft or free agents have hurt the defensive efforts. While I agree that Dallas' offense is superior to that of the defense, that formula clearly isn't working and by the time the defense starts to improve the age/health of the offensive line will be at a point where the focus will need to be on rubuilding that unti which will, like dominoes, impact the QB, RB, and WR play.
That said, Dallas enjoyed more success (even going back to the Aikman days) when they had a potent rushing attack combined with a quality passing attack. Sadly Dallas has gotten away from that approach by investing heavily (Cooper trade, Lamb 1st round pick) in the passing game. Whether people wish to admit it or not Zeke is not the player he was his rookie season and the offensive line is not as dominant as they once were. While Dak has caught the attention of commentators and certain fans with his passing prowess recently, the fact is that Dallas does not win when it's the aerial Dak show.
That is not a shot at Dak but rather the offensive game planning and organizational philosophy. JJ looks at Dak and the WR's like a shiny sports car and he wants to press the gas down all the way for his own personal ego but the fact remains that all going fast does is cost you speeding tickets (aka leaving a poor defense on the field longer), raises your insurance (aka lessens a winning team), and runs the risk of crashing the damn car (aka exposing Dak to injury).
The whole Dallas philosophy is for crap as they would be much better off with an offensive approach that resembles that of a dominant running team with quick passing to game breaking WR's. Not only does this approach protect Dak better in the pocket (his scrambling ability will now be minimized after the injury) but also allow the Dallas defense to remain fresh by keeping them off the field and lessen their exposure.
(In 2016 when Dallas went 13-3 they were ranked 3rd in the NFL in time of possession due to a strong running game. In 2020 Dallas ranked 27th in time of possession. While TOP doesn't always corelate into a winning season, you can't argue the fact that with a questionable defense the less time they are on the field the better the team's chances of winning)