I think you will find that we don't always buy of the shelf because the politicians get involved and look for what can be built in their local area rather than what is best for the job. I can see the merit in that argument but obviously the end product may not be the best.
I think Airforce has got the idea now with its fighter and transport fleet. The tanker and AWAC fleet may not really fit into that but I think in the end they will both prove their worth and there wasn't any real point in buying old technology for those projects.
I think Navy is still under the influence and we are seeing the result with the AWD. Building here a European boat with an American system and we can't even get the 'blocks' right, hold on tight for that mess.
Hopefully the Amphibious boats will work out a little better.
It's a balancing act but in the end you need the best insurance policy for this stuff(within reason), not the cheapest.