I’ve got three kids who grew up with HP and it’s no more shaped their world than, say, Disney - it’s mostly movies, theme parks and merch. Reading-wise, yeah they’ve read them but when discussing gthem now they talk about the plot holes, clunky dialogue and how annoying Harry’s teenage angst is - and this is from teenagers. There’s better written fiction out there (eg the Derek Landy books) plus stuff like LOTR and the Belgariad which they prefer.
There is also a vast amount that is far far worse.
I agree Harry can be a prize twat, Dumbledore was a right arsehole in many ways, Draco is an arrogant little prick and a coward to boot (without Crabbe and Goyle he's nothing but attitude) but the books also gave a lot of MY LOT a good many laughs.
They are also one of few series of books that have been banned from evey library in some States of the US, in some of those some states they still are.
You only have to look at the crowds at the premieres of the films and the sales of the books or the crowds outside the Platform 9¾ shop at Kings Cross to see that twenty years on HP and his crew are as popular as ever, a vist by Professor Sprout a couple of weeks ago nearly caused the shop to be closed to get the crowd orgaised to stop it blocking passengers. This was accomplished with calm and a total lack of ill-humour.
Further, for every person who likes something (virtually anything) there will be someone who dislikes it - that is humanity for you!