Let me offer a different "certain point of view"! From an artistic and storytelling/dramatic standpoint, there was a lot at stake. Rogue One was not one of the main Episodes which could have resulted in diminished importance in fans' eyes. But when I finally saw Rogue One, I was struck with a great deal of emotions to where it was of greater importance to me than TFA.
From the level of passion and attention to detail in Rogue One's making, it was clear the intention was not to just make a "here's one too" movie. It was to insert something that was extremely important directly into the storytelling timeline. And achieving emotional affinity with so many characters within the span of only one film is not an easy thing to accomplish. That the crew of Rogue One and all the supporting Rebels in their fighters and on the ground gave their lives to get that little data disc into Leia's hands hit me so hard, that it gave me a profound appreciation for A New Hope.
The director's minimal use of Vader was perfect, following the "less is more" otherwise we'd want a full Vader film, and that might end up diluting the character down. I watched Rogue One very late in the game after reading on RPF people pointing out problems with the armor, the cod, and how the lighting/mood or lens colors weren't right, etc. I was watching for enjoyment, but also trying to study the helmet from a prop standpoint (which is quite distracting).
The closing scene culminates with such ferocity, energy and desperation that it eclipsed any problems I had with the parts of the costume not either appearing right or interoperating with other parts incorrectly all quickly vanished in the action. I saw the face of Vader and felt fear for the first time regarding him - and this is coming from a guy who has been working on Vader projects for 10 years.
And all those lives, their hopes, their sacrifices, their pain. Those rebels died not knowing if their mission had truly succeeded or not. I was gripped by that realization and felt a pang of loss. In that, the director, Gareth Edwards, succeeded in drawing me into the Star Wars universe and making me believe again.
So I have absolutely no problem with - as Captain Jack Sparrow would say - "borrowing without permission" because if you focused solely on the upper third of Vader in the ending scene, it was enough to be held in the scene's emotional grip. I couldn't be more grateful that Quasimodo played a part in that, but that scene and what it means to me is far greater than Quasimodo as a mask or helmet. It means I have a movie with emotional momentum that will live with me the next 40 years.