1878 is in its way a false lesson since it saw largely small Russian ships have successes against largely inept larger Turkish ships.
The above is patently false on many levels. The
Ottomans had overwhelming naval superiority, so there was no real opportunity - or reason - to employ large ironclads in fleet work, so they were generally not. Why expose a large and expensive vessel to mines and torpedos when a smaller ship would suffice?
The Ottoman fleet's mission was to prevent the Russians from supplying their forces by sea, and it did this. It was also tasked to carry out amphibious invasions, which it also accomplished.
The only failure of the navy in the war was in riverine defense, in which the vessels in question were unfortunately under the control of the army.
To a lesser extent, it needed to provide naval gunfire support, not too useful since the fighting occurred away from the littoral.
But in these tasks it was exposed to torpedo attack, constantly, and it was the Ottomans that pioneered anti-torpedo defense, including the torpedo nets and searchlights that became the norm for all fleets. This war had an enormous influence on European naval thinking, overemphasizing torpedos and mines, because these were the only real potential weapons the Russians had.
If the Russians had possessed any large ships at all, you would have seen gunnery actions that would certainly have influenced thinking.
As it was, there was an action that provoked a lot of thought, the pursuit of
Livadia by
Asar-i Şevket. The latter being a casemate ironclad, was unable to effectively fire end-on upon the Russian ship, having to turn off-course to get guns to bear, which allowed the Russians to stay ahead of its faster pursuer.
That helped feed the obsession for end-on fire and provided impetus for turrets.
So in two regards, one major on another less so, the 1877-78 war did provide lessons for the world's navies.
One, even minor, line-battle would be sufficient to lead to big-gun ships.