Is it possible that those ex-members who say it is a ridiculous idea are viewing this through the lenses of how it was in their day?
No Bob, I for one am not It is too much, too soon and I suspect the real reason is cost. MoD cannot afford enough flight time in 5th generation jets.
Also, what will the groundcrew be doing if the aircrew are spending so much time in the box?
A surge requirement will never be achieved with so much box time whilst real-life core skills are atrophying.