one argument you often see about fanfiction is that it's like 'training wheels' writing? like 'oh it's fine to do that while you're still learning, it's easier than coming up with your own ideas'. and I have to say I have just never agreed with that.
in my experience it's actually pretty common for newbie fanfiction writers to gravitate towards coming up with OCs rather than writing about the canon characters (hence the infamous Mary Sue); this suggests that many people find that 'easier' than attempting to write about pre-existing characters.
I would say that recreating the characterisation, mood and general vibes of an existing work of fiction is in fact a skill in and of itself that's acquired via practice. A common compliment delivered to fanfiction writers is how well they have captured the spirit of the original work. Inexperienced fanfiction writers fail to do this.
When creating an original character you can, ultimately, say anything about them and now it's canon bcos you created them and you said so. conversely, well, if you are covering a well known song and start playing the wrong notes people will notice immediately.
In addition: a lot of fanfiction, IMO, is in actuality a form of metafictional literary analysis. a story where two characters sit down and talk about their feelings about a canonical event? literary analysis, which is of course a skill. Sometimes fanfiction is bad bcos the writer is not good at interpreting texts.
finally I have made this point before but you never really see anyone suggesting that fictional works based on existing public domain texts are on 'easy mode'. is it 'easier' to write something based on a copyrighted work than a public domain work? Of course it isn't.
I know I said 'finally' but I forgot a point:
A major strength of the transformative work is its ability to create dramatic irony. If a fanfiction's emotional resonance is dependent on being familiar with the source material that's not necessarily a bad thing. sometimes it's a sign that the author has done a really skillful job of engaging with said source material.
