I think you are pretty much correct, as those ships were handsome, if fundamentally flawed, even for their intended shallow-water mission in the Baltic (railway guns and other shore batteries would have made short work of them, and of course, the Baltic was the major training ground for the German High Seas Fleet, and there were plenty of dreadnoughts available in the area at any given time to confront them). Admiral Fisher and Churchill were both ardent admirers of the battlecruiser concept, and for good reasons, but you must also bear in mind they were also proponents of the doomed Dardanelles campaign and others as well!
There are a lot of myths and flawed ideas that have been around for a long time about battleships and battlecruisers that have been repeated so many times that they have become ‘Gospel,’ but that doesn’t make them any less incorrect! The idea that either the battlecruiser or battleship became ‘obsolete’ for one reason or another is probably the most egregious. During the first world war, battlecruisers performed their functions magnificently, the hunting down and destruction of Von Spees cruiser squadron at the Falklands is a perfect example. At both Dogger Bank and Jutland, battlecruisers did exactly what they were designed to do, both screening the main battle fleet, and drawing in the battle fleet of the enemy. The fact that some of the British battlecruisers were destroyed is now fully understood as being a function of poor ammunition handling, and failure to learn from previous encounters (whereas the Germans had installed ‘flash doors’ in their ammunition handling rooms, and stored their cordite in brass cartridges, rather than piles of silk bags). Battlecruisers were never intended to directly ‘take on’ battleships at sea, and the failure to follow that precept is the cause of the destruction of HMS Hood in the second world war as well. The main operational argument against battlecruisers as a concept is in reality one of cost, since it costs as much, if not more to build and man a battlecruiser as it does a battleship, and thus in times of fiscal hardship, a battleship is much more ‘cost-effective’ in terms of ‘bang for buck.’ It is for this reason that the heavy cruiser was developed in the interwar period, with its almost identical mission superceding that of the battlecruiser, but at a much cheaper cost. Note that as soon as significantly enhanced financing became available and a recognizable threat appeared, nations began once more to build battlecruisers to augment the heavy cruiser force (French ‘Dunkerques’, German ‘Graf Spees,’ American 'Alaskas), and given the time and opportunity, many more would have been built, despite the so-called ‘failures’ of the concept in the first world war.
Looking at battleships, the common explanation is that they somehow became ‘obsolete’ as a direct result of the rise of the aircraft carrier. This is equally untrue! The battleship was designed to function as part of a fleet or squadron, never as individual ships, and virtually every time they were deployed individually, they suffered terrible losses. This is not because the ships themselves were in any way obsolete, but they were used in a manner they were never intended to. What DID become clear is that battleships and all other surface ships for that matter, would in future require competent air cover to continue to fulfill their function, and it is that lesson which was brought home by the advent of the aircraft carrier.
So, you might ask, if they are so wonderful, why are battleships not still part of the inventory? And the answer to that goes back to my original precept of cost. Quite simply, it is too expensive to either build, maintain, or deploy battleships in this day and age, when there are no other comparable warships for them to defend, or fight against. At the end of WW2, the only nations still possessing battleships were in such a state of economic exhaustion, that battleships could simply no longer be afforded. This was particularly true, since those nations other than the US which might have continued their use (France and the UK) had essentially given up their intent to maintain or obtain any sort of overseas empire. The last use of battleships other than the US involved the Suez Crisis, where the French deployed the ‘Richelieu,’ and after that joint French/UK debacle, it was clear that the old colonial powers simply could no longer afford to flex the kind of muscle needed to continue their old strategies.
This left the US as the ONLY nation still capable of operating battleships, and it is significant to note that every time since then when significant ‘ship to shore’ bombardment operations were required, the US has trotted out their old battlewagons once again, since nothing else in the world either planned or built has the same unique set of capabilities (Korea, Vietnam, First Gulf War). Also, it is significant to note that the last time the battleships were overhauled and redeployed, it was at least partially in response to the Soviet construction and deployment of the ‘Kirov’ class ships, which can only be considered as modern forms of the battlecruiser resurrected. With the collapse of the Soviet navy and the end of the First Gulf War, the US battleships were carefully placed back into mothballs. In other words, if no-one else has battleships, then there really is no reason to have any of your own, and has little or nothing to do with the existence of aircraft carriers (which themsleves could be considered ‘obsolete’ by virtue of shore and aircraft-based long-range missiles).
Is it likely that the battleship will once more sail the seas? Well, history shows that this WILL happen, if another power arises with the might, wealth and will to build them and threaten the current status quo. It will be interesting to see just how long it takes for the Chinese navy to come to this design consideration, and if so, how long it will take the US to either dust off the old battlewagons once again, or consider the creation of a new design (if we are still in an economic position to do so).