Why is it that teams with strong running games are the ones that decimate our defense? The game has changed, but not fundamentally. You still need to be able to run the ball. A good running game alters how a defense plays. It brings safeties into the box and takes away the ability to play pure coverage, 4 man rush. Our own Dak Prescott struggles when throwing against 7-man coverage. Why do you think DTs and LBs are getting paid big money? If you stop the run, the defense functions at a higher level.
The Dallas offense has consistently struggled without an effective run game, and they've been one of the best in the league for several years. This isn't exclusive to Dallas. Outside of Tom Brady and maybe Aaron Rodgers in recent memory, QBs struggle finding open receivers when the offense is 1-dimensional. This allows the pass rush to pin their ears back and feast. Defenders don't have to worry about containment or plugging their gaps. Dan Quinn's defense is a prime example. Absolutely brilliant when the other guys are forced to pass. Terrible when the other team could pound them into dust. You could even look at what Kamara did against Zimmer's defense and the end result, vs what the Browns were(n't) able to accomplish in week 1.
You can dig into stats all you want and buy into whatever metrics you've studied, but it's not going to change the basic fundamental truth...that you need a functional running game if you want to win football games. You don't need to run it 30× a game, but you absolutely need to show that you can do it. Those teams may throw the ball more, but they understand that they need threats at RB if they want to throw the ball effectively. Hence why there were two first round backs in the conference championship games. Did you ever consider that the Niners and Lions invested premium resources into the position because they know a strong ground attack opens up an explosive passing offense?
All of these teams have found recent success in the playoffs because they understand the importance, and have invested into the ground game, regardless of the fact that they plan on throwing the ball a bunch. How does that make you believe that the position isn't important?