Well why the hell did Vader deserve redemption? At least Kylo had layers, some obvious conflict. The great thing about the TROS version is that Kylo’s redemption was a by-product of what was going on. Rey was on mission (both in the DS wreckage and on Exegol) and Kylo’s turn around came about as a consequence of their interactions (and Leia’s death) - not just a matter of Rey throwing everything aside to win his heart. Luke’s entire focus on DS II was saving Vader when he should have been fighting the Sith with every last breath. The idea that Luke became some kind of legend for this is absurd to me. So I absolutely prefer Kylo’s redemption over the cockamamie “Vader was really just a nice dad and you should always support your dad” thing of ROTJ.
The essential idea of ROTJ is simple. Lucas wanted to send the message that even bad people can make a change for the better, so he did it in the most extreme way possible, taking a character who showed no sign of light or remorse in the previous two films, and giving him a path to redemption by way of love for his son.
Whether the turn works for you or you like the idea behind it is a different matter. But I think it’s purposefully extreme to make a point.