Not all fiction is equivalent. When you are actively world building making explicit revisions is useful for those trying to follow along. If you'd prefer a different word you should say so.
I think that’s because the change wasn’t between TOS and TNG. It was between TOS series and TOS films; new style Klingons were in Star Trek 3 (1984) and Star Trek 4 (1986) before TNG started.
Imagine for the sake of argument TOS and TNG are 99% aligned on storytelling and need a patch to make the 1% agree, and that patch is provided in TNG retroactively.
Versus a new show comes along that is 20% aligned and would need an 80% patch to bring it into alignment.
As an executive trying to revitalize a property where fans are complaining about lack of alignment, do you understand why you might just erase the 20% rather than create 80% more of an otherwise-failed project?
>As an executive trying to revitalize a property where fans are complaining about lack of alignment, do you understand why you might just erase the 20% rather than create 80% more of an otherwise-failed project?
If you're an executive, you understand that the purpose of these properties is to make money. Discovery makes money. It has fans. It sells merchandise. You don't erase money because of the rancor of some pedantic nerds, most people do not care.
Cancellation is not the same as "erasure from canon." Lot of popular shows get cancelled all the time - Lower Decks got cancelled as well. Despite the narrative, Discovery was popular. It was a success.
Or that the things that happened in one episode had little impact on the next.