Asturias
There are probably the sum total of about 12 UK citizens (I may have slightly exaggerated that number for comedic effect) outside of the British military that either know or care what an Admiral or a Gp Capt is. You are evidently one of them.
The bottom line is that the senior officers in question are employed to do a job and they do it. Whilst that may no longer mean commanding ships and Sqns they still have a role to play.
The amount of bureaucracy (think Haddon Cave and the MAA for example) that has come about in recent years obviously requires a few grown ups to deal with it.
Whilst we are repeatedly told everything was much better in the good old days remember that things are not the same as they once were. That is for good and bad.
For example, we no longer accept service deaths as just ‘one of those things’ or brush things under the carpet to save face. We have much more accountability these days.
It is not the military that chose to go down the path of massive regulation and accountability but they must stick to it. That requires senior officers to put their name on a document and accept the blame when things go wrong.
If you can actually identify a single senior officer of any service that is not gainfully employed in a job befitting their rank then I would be surprised.
BV