Apparently Rowling is happy for people to write fanfic so long as it isn't porn. She could probably enforce her wishes through the courts if she wanted to- but she hasn't and I think that's because she's a fundamentally nice person. I think it's good manners to respect her wishes.
As a sometime scribbler myself, I've learned that it's terribly important to let go of our creations, especially the ones we cherish most. They're like children, in a way, and with success take on a life of their own.
I don't know, obviously, but it seems possible that seeking redress in the courts could have a negative impact on sales and promotion. If so, I doubt her publisher would allow her to pursue that avenue. Once money changes hands, a new dynamic comes into play and good manners seldom enter into it. Yes, I am a cynical bastard.
There's nothing remotely creepy about the Alice books and I'd be cross with anybody who used Carroll's imagery to create paedophile porn.
At a guess, that ship has probably already sailed. That his imagery has been used for garden-variety porn is an historical fact.
Suppose what I'm getting at here is, why get bent out of shape over Harry Potter and not about the huge amount of erotic art based on everything from The Simpsons to Batman to Walt Disney's Snow White and the Seven Dwarves? What adults get up to and what tickles some fancies boggles the mind. There is no stopping it, has never been a snowball's chances in hell of stopping it. So long as no one suffers physical harm as a result - or financial harm, in the case of pursuing such infringements in court - I don't see a problem, aside from the usual problems when humans are passionate about something.