Pretty sure LeGuin was just a salty bitch about her own boy-goes-to-wizard-school novels not being appreciated the way she wanted. She raged at her publisher for the cover art and shat all over the tv adaptation of A Wizard of Earthsea. She had a lot of unconcealed bitter emotions around how that series was marketed and received.
Most adaptations are. It's no secret what happens to most books that get turned into tv, especially then. Either take the Micheal Caine Jaws IV approach and cash the check with a smile or don't sell the rights. Or use your clout like a certain other author did and insist you be given contractually guaranteed veto power over the casting and script.
I know she's a legend, but everybody told me to start with a short story that I found so contrived and morally facile that I've reflexively loathed her for years.
I don't care how great her body of work was, that story is the most Ana Mardoll flavored thing I've ever read.
I haven't read
everything Le Guin has written, but I did like the Wizard of Earthsea series. However, it is massively different in tone and plot to HP. I seriously doubt JKR got any inspiration from Le Guin.
I've always put down Le Guin books thinking about the themes more than the plot. It's been a long time since I've read Book 1, A Wizard of Earthsea, but I recall some stuff about sacrifice and loneliness. Book 2, Tombs of Atuan is very much about faith and belief and the corresponding lack thereof. Book 3, The Farthest Shore is about death and memory. Book 4, Tehanu, is about aging and regrets and healing from trauma. (Also, it's my favorite of the series. ) The stories feel lonely; there are only a few characters in most of the adventures and the world is desolate and empty. They would never make good movies or tv shows.
Contrast that with HP where there are not only a core group of three friends, but also multiple characters from each House, ghosts with personalities and whole branches of Magical Government. Very different in every way except they both have wizards who go to school.
Of Le Guin's other works, I enjoyed Left Hand of Darkness and its exploration of gender roles. It's well-done speculative fiction and channels Cold War espionage paranoia. (I also feel compelled to mention The Player of Games by Iain M Banks, which is a completely unrelated book that nevertheless has similar Lone Fish in Hostile Pond vibes plus has moments of actual humor too.)
The Ones Who Walk Away from Omelas is all Heavy-Handed Message and nothing else interesting, I don't blame anyone for disliking it or losing interest in Le Guin if that's one's only exposure to her writing.