Like Oberon I had few years away from the RAF, 16 to be precise and I was amazed at how top heavy it had become too. I'm not actually an employee but joined a flying club on a major base. One thing I noticed is that a Group Captain was considered to be good enough to be a CO at one time; this particular unit has an AC and three GPs...
Still, I'm not involved in the whys and wherefores so I suppose there must be reason.