There is a certain benefit to tried-and-trusted systems with known strengths and weaknesses. I'm not advocating lethargy when adopting new technologies, keepin

There is a certain benefit to tried-and-trusted systems with known strengths and weaknesses. I'm not advocating lethargy when adopting new technologies, keeping reliable equipment and weaponry is a good thing. Also, the cost of creating new technologies may not yield significant benefits. E.g. the F-22 is only marginally better (or marginally worse depending on your perspective) than the aircraft it was intended to replace, but at a huge cost.