I feel you misunderstand the role of submarines in WWI and to a lesser extent in WWII. In both wars, attacking warships was a significant part of a submarine's role. Equally, modern submarines are less designed to take on warships and are more designed for the anti-submarine role - though this is nothing new.

In the years running up to WWI, most submarine exercises in the RN focused on attacks on warships. During the annual manoeuvres, submarines would practice attacks on battleships and cruisers; at other times, they would try out the same tactics on destroyers and auxiliaries acting as stand-ins. These exercises were a good predictor for how the RN would use its submarines during the war; most British subs would spend it patrolling the Heligoland Bight, watching for German sorties. Similarly, while the Germans would deploy many submarines to attack Allied merchant shipping, others were retained for use with the fleet. Every major sortie by the High Seas Fleet featured the deployment of a submarine screen off the major British bases. The career of Otto Weddigen is particularly notable. As commander of U-9, he sank three British armoured cruisers, Aboukir, Cressy and Hogue, on the 22nd September 1914, and a fourth (Hawke) on the 15th October. On the 18th March 1915 and now in command of U-29, he attempted to attack a British battle squadron near Scapa Flow; however, U-29 would be rammed and sunk by Dreadnought. One thing that did affect the use of submarines against warships in WWI was their slow speed. This meant that they had to be deployed in advance of an operation, limiting the extent to which they could affect it, especially if it was delayed. There were attempts to build a submarine capable of operating with the fleet, but these were generally unsuccessful - the notorious K-class being the best of the bunch. These used steam turbines and a long narrow hull to achieve the required speed, but these greatly affected their diving capabilities and manoeuvrability. This is one area where modern nuclear submarines have an advantage; their use of nuclear reactors as a steam generator, rather than a fire-box and boiler, allows them to make high speeds, even underwater.

Similarly, WWII-era submarines were frequently deployed and used against warships. Japanese submarine doctrine held that submarines should not attack merchant ships, and should focus on warships. Many of the USN's submarine classes were designated as 'Fleet Boats', because they were capable of operating with the battlefleet. Both of these navies deployed their submarines in patrol lines covering the likely approaches of the enemy fleet in advance of major battles. British submarines were built with a heavy forward torpedo armament. This was intended to allow a sonar-directed attack on an enemy battlefleet from long range, as the RN expected sonar to allow the heavy escort of such a fleet to detect and counter any attempt at a traditional attack. Even the Germans were not shy of deploying their submarines to attack warships, such as U-47's raid on Scapa Flow. German submarines were deployed to cover operations like the invasion of Norway in 1940, as well as to support sorties by heavy units of the Kriegsmarine.

From the 1950s, submarines began to be constructed more for the anti-submarine role. The USN began to construct what it called SSKs, quiet diesel electric submarines with highly effective sonars, to lurk in chokepoints like the GIUK Gap, and hunt Soviet submarines. While these were not successful, with only a few being built, a nuclear version, the Tullibee, was constructed. Most following nuclear submarines were more multi-role, but still biased towards the anti-submarine role - silencing was a key focus, and they had long-range sonars highly suitable for the ASW role. While submarines like the Los Angeles-class were fast enough to keep up with the fleet, they were no longer expected to attack the enemy fleet, but were instead expected to protect the fleet from enemy submarines. Similarly, a key focus in Soviet submarine design was hunting American SSBNs (nuclear missile submarines), and protecting Soviet SSBNs and SSGNs (cruise missile submarines) from American submarines. SSGNs, especially Soviet ones, are designed to attack shipping, but this was not a capability that was available before 1960 because anti-ship missiles did not exist. The anti-submarine role was not a new one for submarines. During WWI, RN submarines had formed a key part of Britain's defence against German U-boats, from patrol lines lurking across U-boat transit routes to submarines hidden beneath tempting Q-ships. The RN even built a class of proto-SSKs, the R-class, for the anti-submarine role. The class was not a success - it was an all-electric design, and the batteries available in 1918 did not give it a useful range - but it did show the importance of submarine ASW. In WWII, British submarines were less focused on the ASW task, but would still attack U-boats when they encountered them. Nineteen U-boats were sunk by Allied submarines. One of these, U-864, sunk by HMS Venturer, in February 1945, is the only submarine to have been sunk by a submerged submarine while it was itself submerged.