Remember that in Enid's day there wasn't much else to read that was specifically for children.
Really? Her first books were published in 1922, but her peak was in the 50s. There were plenty of books published over those times.
I collect children's books and there is no shortage of books over that time.
For me, I don't see them as sexist. Anne is a girl who likes playing house-as some children do, and is also the bravest as she realises how dangerous a situation that they're in, but goes ahead anyway. Julian is the leader because he is the oldest. George was for the time is quite forward thinking. Why did people always assume she was a boy, even though it's pointed out she doesn't really look like one? Because she did the things the boys did and wore boys clothes. Nowadays people wouldn't assume she was a boy because it wouldn't be that unusual.
They're clearly dated-housekeeper, tutors, boarding school, quarantine. So children are more than capable of realising that some of the things in it are dated.
I've just started reading ds a book set in Shakespeare's time (The Player's Boy, Antonia Forest). There's quite a lot of explaining going on at this point, but I doubt he's going to ask my neighbours tomorrow if they're worried about being arrested for being a Catholic.
However in Enid Blyton I do think some of the racism does need to be altered. Jo Jo is one of the cases in point. She uses her view on his race to make him sound bad. I wish though they would do it in a sensitive way and actually rewrite the passages rather than taking the sentences and altering them in a clumsy way, which is what I've seen.
Other things I don't think should be altered. Again £ s d gives the books the period feel. And Dame Slap to Dame Snap totally changes the story. My children when reading it thought she was meant to be a figure of fun rather than someone who was actually scary. And I don't think it phases children to come across it in writing either.