cokecan,
IIRC, far from this being simple US showing off, somewhere in their doctrine it states that they will maintain a level of superiority X times that of their allies and 4X times that of potential opponents. In effect, our attempts to keep up with the latest technologies is doing nothing more than breading an arms race amongst allies as well as opponents.
That's fine, but if the rest of the world decided not to try and keep up, then the US wouldn't feel the need to keep advancing at such a rate and to such an extent, and indeed might end up finding itself the odd one out and decide to ease off for a while. And seeing how few platforms we have these days - across all the Services - I for one would be more than happy to ease off the accelerator a little if it meant we were a little more sustainable by virtue of having greater numbers.