No, I think Dahl was a genuinely fantastic writer of children's stories, even if the morality may be somewhat off some modern ideals.
He writes as someone who really tapped into how many children feel about the world: an ability for children to see themselves in his protagonists - including some of the darker sides of mischievousness, other troublemaking, and resentment of adult authority.
He has a take that the world is a harsh place - as someone who had been through a particularly brutal boarding school and was brought up on novelists such as Dickens might do. But his protagonists, whilst not necessarily paragons of virtue (what children are?), are smart, resourceful and fight against injustices and to overcome trials. In the end, they usually find happiness in loving and supportive, if not necessarily conventional, families. In this sense, I think one thing that does come through from Dahl's stories is a strong, core of belief in goodness and kindness, even if he was too flawed to live up to much of that in own his personal life and had notions of race and gender pretty typical of his less enlightened era. (He was highly altruistic in some respects, mind.)
There's plenty of room in children's literature for authors like Dahl.