I don’t think the majority of readers really care about well-rounded, flawed characters, character development, engaging plots, or really anything of that sort.
And hear me out.
I recently watched a video of an author advising how not to write a Mary Sue, that Mary Sue characters were bad, that it’s poor writing and all of that stuff; but the example they used was Bella Swan from Twilight.
You know, that series that everyone allegedly hates but that has sold over 160 million copies worldwide.
If Mary Sues are so terrible, why are hugely popular books starring them so successful? If writing a Mary Sue automatically meant the book was unengaging or boring, why is Twilight so popular?
Bella Swan has no agency or character development, so why is the book so popular among readers?
I don’t think Mary Sues are the problem, because I’ve seen a ton of readers requesting those same characters in book recommendations.
Heaps of readers are actually really lazy and don’t want anything with character development. They want instant gratification (which is hard to do in a book if you start your character off in a place where they might learn and grow). They want instant badasses who are already perfect and don’t have any character growth because they literally have no flaws.
Case in point: Celeana Sardothian from Throne of Glass and Feyre from A Court of Thornes and Roses. Even Violet in Fourth Wing, despite her disability, is identified as being special right from the start of the book.
Any characters that DO have flaws are seen as imperfect, and not worth investing in, because they don’t play into the reader-insertion wish fulfilment that so many readers crave.
This is why Bella was so successful: because she is a blank canvas that readers can insert themselves into.