I should qualify my disdain for bullet sponges. I can totally understand a battleship (Cutter, Corvette, Conda, etc) being a bullet sponge. When a small ship like an Eagle can eat bullets for even 30 seconds from an engineered Mamba, THAT requires a suspension of disbelief that just ruins things like CZs for me. Now contrast this to the Harmless Eagle NPC which I can one-shot with another small ship, and I start asking myself, "Is there Vibranium in Elite Dangerous? Is this Tony Stark's Eagle?" You can thank engineering and HRP stacking for this.
But if it takes me all day to sink a "battleship", then I'm fine with that. In some ways I prefer it, as it makes sub-targeting much more useful (I always kill Cutters via their power plant, for example).