Look,
there are no corners on this team besides maybe Bowman that I want bumping and running. Even if you have safety help the corners have to slow the WR's down enough for the safeties to be effective. Especially with a two receiver side. Its what your theory for point one is. But look at the Vasher play, he didn't slow anything down. You have to have a certain type of corner to play that.
And our CB's dont always line up 10 yards off the ball. They change their depths throughout the game.
Again this type of defense is designed to prevent big plays and get turnovers. Its going to give up yardage. Thats just the nature of the beast. Although people dont like it, its what we run.