The good old days where lore was a thing...and fictional universes were taken seriously and each change required a lenghty explanation and a great story to be told in ordr to justify those changes.....ehh those were the days. Now instead we prefer to call this new lazy approach "artistic freedom" and change midway established lore and races because it's "cool"
Those "good old days" have very little to do with fiction. The written version of the
Iliad contains internal continuity errors, like Pylaimenes, who is killed by Menelaos in Book V and yet is still alive in Book XIII to watch his son die. (Such Homeric nods are one of the many reasons why Homer was not a single person, and why
Iliad and
Odyssey were more like modern shared universes than single-author IPs.) Daniel Defoe larded
Robinson Crusoe with continuity errors, like how Crusoe swam out to the wreck naked and filled his pockets full of biscuits before swimming back. As for retcons, Conan Doyle resurrected Sherlock Holmes to make a few pounds and shut up his annoying fans, and did it by having Holmes say "haha I was in hiding this whole time!" Tolkien also made goofy, lazy retcons, like when he decided to completely change how Bilbo got the Ring in
The Hobbit, and explained the original version by Bilbo saying "I lied about it lol good joke huh". He also tried a Darker and Edgier full reboot of
The Hobbit that fortunately didn't make it more than a few chapters.
Fiction is a vehicle for telling a story; the setting is an important part of that story, but only just a part. What you're referring to as "lore" has a lot more in common with theology than fiction, where the "lore" is religious truth and changes to it are heretical. "You can't just insert that 'and the Son' part in the Apostles' Creed! It wasn't in the original!
EXCOMMUNICATED!"