The fatal flaw in HOOD (or any battlecruiser) wasn’t the lack of armor, it was how they were employed. BCs looked like battleships, sounded like battleships, and fired battleship guns, but they had no place in the line of battle, where speed counted for nothing. If BCs had been confined to missions where speed was important, like scouting, or running down armored cruisers that were harassing convoys, and beat feet at the sight of any proper BB, their reputation may have been very different.
Speed is important in any tactical planning. The basic speed for all fleet escorts has been set for 75 years by the speed of the aircraft carrier, which needs to be fast enough to generate her own wind if she has to. I can remember chasing KITTY HAWK around as plane guard and watching her absolutely walk away from our DDG traveling at full speed - it’s a humbling experience.
Survivability is also a relative term. COLE, STARK, FITZGERALD, these ships were all taken out of the fight for one reason or another, but the trend is the same: it was a single incident or attack that laid them up. One hit may not be enough to sink a modern ship, but she will most certainly be a “mission” kill. Some vulnerabilities could theoretically be addressed with armor, but others, like radars and other electronics, can never be protected behind steel plate. The days of staying in the fight after multiple kamikaze hits or slugging it out against another ship with gunfire are long past. The way you survive is to not get hit in the first place.
Which circles back to LCS. Even if she could make 50 knots that’s still about 700 knots slower than the average ASCM coming to make her a mission kill. Was the trade off in other capabilities worth it? I’m inclined to say no, but they didn’t ask me. My great fear is one day, if the Navy continues to add LCS and not enough fleet escorts, that some admiral will decide that LCS look like destroyers, sound like destroyers, and fire guns like destroyers, and place them in carrier strike groups. If that strike group goes to war those LCS will probably join all their Jutland BC brethren in short order, leading the commander to remark that “there is something wrong with our bloody ships today”.