I think ideas about redemption, forgiveness, and the ability to finally choose to do the right thing (even after making terrible choices) are baked into the thematic and spiritual DNA of what Lucas wanted the STAR WARS Saga to be about (in terms of what it's saying about the human condition). So going there with Ben seemed like the only viable option if this trilogy was ever going to feel truly connected to what came before.
I'd have rather seen Ben make it out alive and, knowing that he can't be truly accepted by most people because of his actions as Kylo Ren, set out into the galaxy as a kind of wandering figure, slowly atoning by helping others where he can. It wouldn't have been so close to repeating Anakin/Vader's arc.
But if it was a choice between what we got and Kylo dying an unrepentant bad guy, give me what we got. All day.