I wonder about the thought process of the coaches, but then I think I can see a bit of what they are thinking. Hear me out...
We watched the 90s with Cowher, the Steelers had that great running game and controlled the clock. But they would get into the big games against a team that could do multiple things and they'd get beat. The thing about a dominant running game is that you are not scoring in bunches, and it keeps other teams in the game. A few quick scores by the other team and next thing you know you are losing. That usually didn't happen with Cowher because of the defense, but the issue remains.
Look at this year. The Steelers gave up 201 to Tennessee, 185 to Cleveland, 249 to Baltimore on the ground and still won those games. They gave up 246 to the Vikings and perhaps could have won that game because of a few big plays they made.
My point is I think I can see what they may be trying to do. Limit the scoring in bunches. I'm not saying they are right, I can just see the argument.
IMO, the Steelers need to get back to doing a few things really well, like run the ball and stop the run and build from there. Right now, they don't do anything well, which I think is a problem with this desire to be multiple.