A lot of this comes down to how we fight wars these days.
Back in the WWII days, we had very large numbers of fairly simple weapons. They cranked out guns and tanks and planes by the thousands, and thousands of men went into combat.
There’s a bit of a philosophical difference between the way that the US does things and the way the Russians do things. While both tend to have much lower numbers of much more high tech weapons, the US is focused on very small numbers of very high tech weapons, and Russians have much higher numbers of much simpler weapons. There’s a certain quality in quantity, as the old Russian saying goes.
With our focus being on very small numbers of very expensive and very high tech weapons, we can’t scale that up very easily or quickly.
In the past several decades, this strategy has worked very well. We haven’t been in any kind of all-out war like WWII, so we haven’t needed the huge numbers. Our high tech planes were able to completely destroy the Iraqi air force in a very short amount of time. In WWII, if you needed to take out a factory or a bridge, you sent hundreds of planes over that factory and carpet bombed it. Most of the bombs missed their target, but enough would hit close enough to take it out. These days, one plane with one or two well placed smart bombs can accomplish the same thing, with much less collateral damage.
There is a bit of a danger with this strategy, and the German King Tiger tank of WWII is the typical example given of why this can be a bad idea. The King Tiger was by just about every measure the best tank of the war. Put it face to face against a Sherman tank, and you could let the Sherman fire first if you wanted. The Sherman couldn’t penetrate the front armor of the Tiger. But the Tiger could easily put a shell in through the front and out through the back of the Sherman (which was very bad news for the crew and everything else inside it). The Russian tanks fared a bit better, but even they were under-gunned against the Tiger.
The problem was though that the Tiger was monstrously complex and very difficult to build. The Germans would have been much better off taking the same amount of manpower and making their less capable tanks with it. They would have been able to field a lot more of their “inferior” tanks and would have had a much better presence on the battlefield. The Tigers couldn’t be produced in large enough numbers to be useful on the battlefield. It took on average four Shermans to take out one Tiger, but we were cranking out ten Shermans to every Tiger. The Russian tanks were cranked out in huge numbers as well. The Tigers, despite their superiority, were simply outnumbered by staggering amounts. There was no way that the Tigers could win that fight.
The same sort of thing might happen if the US and China or the US and Russia went to war. We have the best weapons, but they are difficult to produce.
Many argue that an all-out war between us and China or Russia would likely end up nuclear, so our lack of producible weapons may not be that big of a deal after all.
One valid criticism of the stealth bomber though is that it is too expensive to risk using it in combat. They did use it a bit in the second Gulf war, but only when the risk was minimal.