The real question is: why does anyone care about having a consistent canon?
It gives a world a feeling of realism and depth when you can look at any one part of it and think of it as part of a larger whole. Information you get from one part can be applied to another part and vice versa. For example when you watch the movies and see Palpatine and Vader doing Sith stuff, you can fully appreciate that they’re part of a 5000 year tradition and a 1000 year plan within that tradition. You can play a video game, watch a movie, read a comic book, and it all “counts.”
When it works it’s really cool. The issue is that when massive duds come up, the people making the whole project have to consider them canon to stay consistent.