I think if you ever try a game without objectives, you’ll see why there’s newfound value in the gun cruisers. They can hit without being hit by smaller caliber arms.
The Germans have great gunned cruisers but the best armor is a 4 which is can be hit with destroyer MG's. So they are expensive and can lose the ER4 rather easily. American heavy gun cruisers have armor 5. That extra point means a lot when you get to fire from ER4.
I made a custom card for Graf Spee. Keeps same stats and 21 point cost, but adds SA "Avoid Engagement". This gives the chance to keep ER4 maybe a turn or two longer.