I visit the bookstore with my kid regularly. She's 5. My older kids 11 and 14 do find plenty to read, but I disagree that there are plenty of magical modern children's authors capturing the 3 to 10 year old space. There are a lot of books, mostly dross.
And the stories... "I loved my cat/mom/dad then they died" I get it sad stuff happens and kids need to process it but these aren't books that are going to delight. "Your cat died so I got you a book about someone's cat dying"
Dahl's best-known book is about a family of 7 that can barely afford to eat. One of his other famous books is about how giants stalk through the night to kidnap sleeping children and eat them. A third one is about a child prodigy who is treated to the point of mental abuse at home, finally gets to go to school, only to encounter physical abuse - by the folks that are supposed to keep her safe!
If you think those stories can do more than terrify and scar children for life, I see no reason why you'd be dismissive of other works in which far, far less horrible stuff happens.