I admire your optimism but in reality I feel there are far more people like Cozy than we can possibly know, past and present.
Some say good and evil right and wrong are all just concepts at the end of the day, concepts that nature and the universe itself doesn't adhere to. That they are Human constructs by which we measure our actions.
That said take the actions of Ted Bundy or Jeffrey Dahmer, pretty hard to justify any of their actions as anything but true unadulterated evil with no chance of redemption or pardon.
I gather your argument is that in order for Friendship is Magic to give a positive message it needs to follow a specific strict formula that kids shows have been doing since even before the medium itself eg most religious texts, bad guy turns good and good always conquers evil light vs dark etc.
Don't you think that would become repetitive predictable and dull by season 9 of any franchise?
Like I said I think children for the most part are perceptive enough to pick up that Cozy is not somepony to emulate and idolize as a hero because they understand how the show portrays her in a less than positive light and that it is not real anyway. Unrelated but related, what are your thoughts on the violent video game debate?