There were people who hated the animated series and didn't want it to be part of "their" Trek. There were people who hated ST:TMP and TWOK and didn't want them to be part of "their" Trek. There were people who hated TNG and didn't want it to be part of "their" Trek. And so on. If the tie-in creators heeded purist fans' desire for building walls between old and new interpretations of the franchise, we wouldn't have two Trek universes now, we'd have at least half a dozen, all mutually incompatible and forbidden to share ideas. And that would be a much less interesting universe.
And you know what? I've managed to come up with interesting stories based on ideas from episodes I disliked. Just because a character or idea originated in an installment I thought was bad, that doesn't mean it can't be the basis of something worthwhile in a different context.