Does canon vs. non-canon really matter in the home video era? I own it and can watch it whenever I want.
Well, by current definitions (remember, Roddenberry's definitions ceased to apply when he died over two decades ago, so it's rather odd that fans are still up in arms about them), if it's onscreen, then it's part of the canon.
And again, canon is not, has never been, and never will be about telling the audience what they can or can't watch/believe/enjoy. That's a myth and a fundamental misunderstanding of the concept. After all, it's all fictional anyway, none of it more real than any other part. Although the term "canon" comes from religion and implies that texts outside canon should not be read at all, it's silly to apply that same dogmatism or exclusionism to a fictional
canon. If you enjoy a story, you should be able to enjoy it just as well whether it's part of the official/original continuity or an apocryphal tale.
I like to say that if canon is history, then tie-ins are historical fiction. They're stories that aren't a documented part of the "real" history, but that potentially could have happened within it -- at least until some new "discovery" is made (in some new episode or movie) that proves they couldn't. And it's not like watching TV or movies is a history course where you have to get the right answers on a final exam. It's strictly recreational. I'm sure there are plenty of people who enjoy reading both historical nonfiction and
historical fiction. If you enjoy history, then both can be valuable. You may know that the latter probably didn't happen, but it can still be entertaining to believe it could
have happened, and at least it can give you the pleasure of imagining yourself in the historical setting you enjoy.
And of course, unlike real history, canon is just as imaginary as the tie-ins derived from it, so that makes the distinction even less worth making a fuss over.