The complaint about the epilogue mirrors one of Orwell's complaints about Dickens's happy endings:
"This is the type of the Victorian happy ending — a vision of a huge, loving family of three or four generations, all crammed together in the same house and constantly multiplying, like a bed of oysters. What is striking about it is the utterly soft, sheltered, effortless life that it implies. It is not even a violent idleness, like Squire Western's."
To Dickens, and apparently to JKR, the object of going through all these vicisitudes is precisely so that you can arrive at safe, sheltered domesticity. Adventure and challenge are not to be sought out -- they are an infliction to be overcome so that your children will never have to face them. The generation of parents who lived through the Depression and World War II felt the same way. We can console ourselves that the next generation of wizard kids will react ungratefully against their parents as the Boomers did. Now there's a sequel -- the wizard equivalent of the 1960s.
Orwell also pointed out that Dickens had no idea how things worked economically, and that the reader had no sense how his better off characters made their livings. JKR's invented world likewise doesn't include an economy. Except for teachers, bureaucrats, journalists, shopkeepers, servants and the driver of the Knight Bus, we have no idea of the characters' livelihoods. Where does the Malfoys' money come from? How do Hermione's parents raise the wizard currency to pay her tuition? Is the Ministry of Magic supported by taxes? Why are there richer or poorer wizard families, and why, indeed, does the magical world need money at all? Is there a sub-wizard human population to manufacture cauldrons and grow food for the wizard world?
JKR's primary audience of children don't, for the most part, ask questions like that about their own world. Food is what's in the supermarket, and work is the incomprehensible things adults do out of sight all day. It isn't exactly fair for adult critics to complain that she hasn't answered such questions, but it is a sign of the completeness of her fictional world that we ask them