Why so insecure? The point of posting anon is so you can say what you think without having to worry about how you sound to others.
For me, the open-world creativity was also a huge part of the appeal in the beginning. The indeterminacy, the feeling of anything being possible, it was exhilarating. Now there is a lot of canon and if you want to adhere to all of it, it can feel constraining.
To me, George Pollack's Tales remains one of the best fanworks. Some say it has aged badly. I disagree. The wild divergence from canon is a feature, not a bug.
In general I'd have to say that I prefer stories which piss in the face of canon--and more importantly, fanon--and do their own thing uncompromisingly. While such works are usually not remotely plausible within the world of canon, they are more free to have integrity in the sense of being a unified whole. They are free to do what the logic of the story itself dictates should be done, rather than merely following an approved set of tropes and pre-existing ideas that have grown hoary with age.
Many people use OCs for such projects, but OCs don't have the same impact. The key, in my opinion, is to look at the characters of the show more as archetypes than as fully fleshed-out characters. The canon represents merely one set of possibilities for these archetypes to realize, and tells one set of stories that could possibly be told using them. The same goes for the universe, Equestria. It is the world of possibilities, a Dream Land. Equestria is every bit as compelling a setting as Middle-earth. Everything you need to know about Equestria to write about it, you can learn from watching the first two minutes of the pilot episode. What's essential about it is not its exact geography, not that it exists here or there or has these boundaries; what's essential about it is what it means.
I would personally like to see more inventive stories that explore the possibilities for this world and these character archetypes in ways that haven't been explored before. If that means contradicting canon, so much the better.