An interesting point!

By American Naval standards a surface fleets purpose is to compliment and protect it's aircraft carriers. As the Graf Spree never saw past 80% completion the Kreigsmarine was a Battleship Navy and used them to intimidate thier foes. The Admirality wasted many vessels in vain in my opinion. ie. The Bismark obviously and the Blücher lost to Norwegian coastal defences. Dedicate the science to upgrading the Unterseeboot flotillas with more effectrive weaponry. In all reality the majority of the commerce raiding was done by U-boat anyways. and dedicate the raw steel and manpower to the real fortification of Western Europe. Now if only they had remembered how cold it can get in Russia we might all be living in a Nazified global Reich.

Nevertheless I think the point is valid. They tried to do to much instead of being really great in certain aspects.