The trouble with a high turnover of younger servicemen is that it is murderously expensive. The length of training vs return becomes disproportionate, the balance of those in training or instructing vs productive degrades FE@R or requires a manning uplift
JTO,
You're basing your argument on logic and long term thinking, neither of which feature in many politicians' calculus. Especially the current lot's thinking which actually mirrors society very well in its desire for instant gratification and an attempt to look good despite the reality of the situation.
In effect, we have a Facebook government for a Facebook generation. Don't be surprised if they haven't considered the long term implications, they're more concerned about getting to the next level on Angry Birds.