Mistborn: Secret History

On one hand I admit that it really didn't feel like Kelsier's story was done after the first book and I was kind of expecting some hints in later novels.

But this is it? This feels like a fan fiction written by the author himself! It completely reveals all the secrets about the Mistborn series and Scadriel in general. I would've prefered to be kept in the dark or at least to think that all of this was the work of Preservation and not Kelsier's.

The Cosmere connections I liked but gutting the original story and “revealing” that all those things Preservation supposedly had done were actually done by Kelsier broke all the magic and mysticism of the series.
I wanted to know more and if the story focused more on the elder ones (or whatever they're called), other travellers and the actual secrets of Cosmere I would've loved this novella. But it doesn't. Instead it focuses on the trilogy and reveals that every important act done to further the plot was actually done in secret by Kelsier and not by Preservation.

And so I can't accept it. I don't want to accept it because it ruins otherwise great and supremely original story and degrades it to the mediocre levels. Maybe I just pictured everything better in my head and this book shattered my image and now I can't accept the mediocrity of it.

However, I admit it got better towards the end but even that's mostly because Vin is probably my favourite female lead character.
Still, though, I wish I've never read this novella.

If Mistborn was a videogame, this novella would be infinite ammo and life cheats :/