The Russian thrust vectoring technology is contrary to low observability from behind and this is one of the arguments against it. If I understand correctly, the F-22 has some thrust vectoring which is 2-directional unlike the Russian 360 degree thrust vectoring, but the F-22 also has very low observability from behind unlike the Russian Su-57. So the choice in this trade off seems based on tactical doctrine.There are those in the west who claim that the thrust vectoring capability looks very nice at airshows but has no tactical use in combat, especially aerial combat. However the Russians have different CONOPS to the US military, RAF etc., and they aren't as enamoured with long range engagement as the USAF / USN, being quite happy with a merge and knife fight if the opportunity presents itself. That's where they see thrust vectoring as giving them an advantage. They also use it to shorten landing and take off distances. I gleaned all of this from the three videos on the Su-57, two of which were posted by @Ananda in post #1,925 and the video I posted in my post #1938.There's a few big ifs in the Su-75 Checkmate program, with the biggest being will Sukhoi deliver on what it's promised? Time will tell.
However the concept itself isn't silly and one that probably should be seriously considered in the west, most likely the US. Take the current technology from the F-35 and utilise it for a 5th generation light fighter. There is no need to invent any new technologies because you would be acquiring MOTS and COTS to build it. Costs can be reduced by building a digital twin. Something to think about.