While I don't disagree I think it's important to keep in mind that kids and teenagers aren't stupid - they are capable of understanding that you shouldn't allow a bad person to continue to be a bad person if you have a conversation about why what JKR is doing is bad. Most of the vocal pushback that I've experienced offline has actually come from teenagers.

The problem lies squarely with millennial parents who continue to buy books/movies/games/merch for themselves or their young children because of nostalgia. They are old enough to know better, and should be held responsible for their actions.