You call that brilliant executed? It was a 10 second flashback with little context, they basically said the guy who never gave up on his father, Darth Vader, gave into doubt sudden with his nephew? That snoke from across the fucking galaxy was poisoning his thoughts? It was shit tier execution with terrible/no build up, just thrown at us as a surprise!
If you don't want to proper build up this monumental fuckup/failing of a major character (lets be real, while Luke isn't the main character of the sequels, he is a major one, and was a driving force in people wanting to see the film, as the character has a massive legacy) and instead we got, cause it happened!
Honestly would have been 1000x better just to have him send Kylo out on missions to prove himself a Jedi, and Kylo run into Snook and fall to his corruption, and that cause Luke to feel he failed as a Teacher/Uncle and abandon his work starting the order again. Even then I don't think the character of Luke presented in 4-6 would have fucked off to an island and ignore his now evil Nephew and abandon his sister, like he did in the movie. Sorry my expectations for movies is higher than that.