The rams were quite useful against one’s own ships, during training exercises they caused several total losses;
To quote the comprehensive and all knowing WIK;
“The scale of Hood’s protection, though adequate for the Jutland era, was at best marginal against the new generation of 16-inch (406 mm) gunned capital ships that emerged soon after her completion in 1920, typified by the American Colorado-class and the Japanese Nagato-class battleships. The Royal Navy were fully aware that the ship’s protection flaws still remained, even in her revised design, so Hood was intended for the duties of a battlecruiser and she served in the battlecruiser squadrons through most of her career. Late in her career, Hood was outclassed by the armour and protective arrangement of World War II-era fast battleships, but few available “big gun” vessels could match Bismarck’s speed, and in 1941 the Admiralty included Hood among the ships sent to engage the German battleship”
“Hood’s armour scheme…was angled outwards 12° from the waterline to increase its relative thickness in relation to flat-trajectory shells. This change increased the ship’s vulnerability to plunging (high-trajectory) shells as it exposed more of the vulnerable deck armour. 5,000 long tons (5,100 t) of armour was added to the design in late 1916, based on British experiences at the Battle of Jutland, at the cost of deeper draught and slightly decreased speed.”
“To save construction time, this was accomplished by thickening the existing armour, rather than redesigning the entire ship”
These facts address the flaws in the Battlecruiser concept, which they often refer to as “An Eggshell with a Sledgehammer” (also applied to AFVs before reactive armor) which was that the ever increasing weight of armor could not ever dynamically complete with improvements in shell and gun because a technological advance was needed to create a plausible defense. Instead, they just kept trying to tack on, revise or add more armor, which only made the ships slower.
While extreme-range gunnery is fascinating, as others here mentioned, “ranging” or finding the OPTIMAL range for hitting is more important than theoretical range, during actual pitched fighting many shells were expended (esp. by Royal Navy) emphasizing rate of fire and saturation of an area rather than truly “aimed” fire. This is where speed comes in, because the faster ship can pick the range it prefers, then maintain that range throughout the combat, whereas the slower, heavier, better protected ship probably could not.
In addition, Hood was new and advanced in 1920 but outdated and worn out in 1940. The kind of ammo explosion that sank her is common in tank ATGM hits, a “cookoff” where any ammo or fire can cause a runaway event, igniting fuel and then more ammo, causing a “deflagration” (ie total, immediate, loss).