The problem is that Kronner, E and DD are NOT fine. It's not like those guys are reliable night in, night out and the other 3 are costing us. Kronwall has gone through a couple weeks of terrible play recently, E was just about the worst defender against Florida and apart from his first game back, has been shaky since his injury, and DD has shown enough times that he's still a rookie since coming back too. What's more Quincey has actually been pretty good over a few games.
Every time I see JoesufP or Dabura bemoan the lack of a top defender after a goal against in a GDT, I wonder "how is this magical defender that we can't afford going to be able to be on the ice at the right time to fill in for whichever of our 6 defenders is going to decide to turd it up on any given night?"