With lots of Allies backing them up in both of those conflicts and considering the time past until now, yes they may have a similar sense of bravery and brutality as back then or maybe not due to the presence of all these problems with cohesion that quite frankly is a growing problem along with recruitment difficultiesNope. Based on what I have read and heard from actual US military veterans and personal and past, but now deleted, posts and the livestream from @Patchwork_Chimera who quite literally talked about this issue, unlike their political counterparts, the US military is taking the Chinese extremely seriously. Aside from that, in regards to motivation, motivation and espirit de corps are huge morale multipliers because they drive military personal to do courageous and/or sometimes brutal things to their enemies. For example, the PLA's conflicts in Korea and Vietnam, and the second Sino- Japanese war all showed how motivation and spirit maintained unit cohesion and allowed them to continue to stay in the fight.
In the end, this will ultimately amounts to nothing unless they have enough forces to back them up in an actual fight and comparing the US military to what it was in the past to now will show a stark contrast that is hard to ignore. If they were so brave about taking China and Russia at the same time with the current stockpiles they have along with a bunch of Allies they have all but spent there military gear in this conflict in Ukraine, then the leadership must be on drugs because even the pentagon is in no true rush to get into a fight so quick without the necessary stockpile and supply chain issues addressed along with having enough man power since nowadays, most of the military personnel should be quite aware of how well the USA treats its combat veterans which to be quite honest, sucks a lot, which does help to explain a little why recruitment issues are mounting
