[coin]

That still doesn't explain the low total time limit. 5000 hours is low compared to the typical 50000+ hours that modern jets are rated for.

[dragonwriter]

Modern jets aren't prop-driven Soviet strategic bombers. They are typically built for comfortable, cost-effective, long-term operation, not to be a credible threat to deter (or carry out) a life-or-death war with an economically far more advanced adversary.