It’s pretty clear that hypersonic missiles are very effective because current air defence systems aren’t able to shoot them down. This allows for doing deep strikes behind the line of contact with impunity. It’s quite obvious why US would desire such weapons, and in fact has been trying to develop them for around a decade now without success.
These missiles also don’t cost a billion dollars for China or Russia to make because they’re produced by state industry that’s not run for profit resulting in costs being orders of magnitude cheaper than they are in the west.
The whole purpose of US war industry is to suck up as much tax money as possible and put it back in the hands of the oligarchs. It’s not meant to produce cheap and effective weapons because that’s not profitable.