Defense Secretary Robert Gates has been negative about advanced military systems that do not have immediate application in the sort of low-intensity warfare in which the U.S. has been involved in Iraq and Afghanistan. He has been pushing the military to emphasize immediately practical technology, like MRAP (mine resistant ambush protected) vehicles and UAVs (unmanned aerial vehicles).
The war now in Georgia, prominently featuring Russian tanks and attack jet aircraft, has started a change in defense thinking. An article in today's Wall Street Journal (Aug. 16, 2008, p. A6) makes the point that cutting edge systems like the F-22 Raptor fighter jet and the Zumwalt class advanced destroyer are gaining new attention. It makes sense. If we have to be ready to fight the Russians or Chinese, MRAPs won't help much and F-22s will help a lot.
As long as the U.S. insists on being the world's policeman, we need to have both capabilities: low-intensity anti-insurgency warfare and high-intensity high tech modern battlefield warfare. To continue with the police analogy, we need the traffic cop as well as the SWAT team.
Postscript: It might make sense to have military units specialized in, and equipped for, one or the other of the two types of warfare, if we can justify having that many in uniform.