Paul Farquhar
Legend
Milton and millions of other writers since have pulled it off. Despite Marvel's problems in the area you don't need to be a literary genius to write a relatable villain. And when it comes to theatre/film/TV its as much down to the actor's performance to sell it as to the writing. And clearly, when you are writing a story about the rise of Sauron, Sauron has to be a relatable villain protagonist. IMO RoP pulls it off successfully.The audience need not be modern. Milton does exactly this with Satan in Paradise Lost. The idea is hardly new.
The cost is that Satan is no longer a mythotype; he becomes a humanised protagonist.
But it’s hard to execute well. Milton pulls it off, but his writing skills were rather better than P&M.
Sauron is an absent character from the story of his defeat, so his motives are not relevant. However, he is punished at the end, by being permanently banished from Heaven, so the author clearly considers him guilty of wrongdoing. Indeed, he receives the exact same punishment as Saruman, a being of the same essence who clearly had a choice and chance for redemption.
More significantly, RoP rather cleverly managed to give the orcs a choice and chance of redemption, thus fixing a problem Tolkien himself had with LotR.