I know the canon debate is a ongoing one and with"Discovery" it seems to have become even more of a issue. To me I think the value of canon is to make the shows feel like they exist in a shared universe, were even if you see alterations, you still feel like it is all taking place in the same universe. To me this adds greater depth to the shows because it helps make your universe feel like a real place. Without it then you basically would just have some 50's style aproach to sci-fi were no real thought is put into the details and everything comes off looking inconsistent. No need to think about the tech or why humans might be on a spaceship. All that matters is the story which in turn also feels unimportant because you don't buy into the premise. A future setting is always going to feel unrealistic no matter what, but things like canon and continuity do help ground the unrealism and make it seem somewhat possible.
Jason
Jason