First of all, we can absolutely use the author's beliefs and intentions to determine or guess at canonicity in most cases.

Second, there are way too many heroes to play.

Third, an author and their interactions with the community, clarifications, etc. often add further details to the worlds they bound in ink, and IMO it's pretty valuable to peek into what they built while they're literally still alive.

Fourth, there's no camera follow and that's pretty frustrating.