One can argue which of Lindgren's books is the best or the most seminal, and certainly, many of them are probably better-suited to somewhat younger children (but then the same is true for many others, as Tom notes), but not including any of them is a shocker.

As far as Ende goes, I'm not all that enthusiastic about The Neverending Story actually, but Momo (or "The Gray Men" is hands down one of the best children's books out there.

Other than those, I would include two authors who are exceptionally good at writing about and for teenagers (after all, 11-year olds are teenagers, nowadays): Aidan Chambers and William Bell. Chambers is British and certainly gets the recognition he deserves, so not sure why he was left out - unless of course it's because he writes more for the kind of 11-year old that many of us were, and not so much for the kind of 11-year old reading the books on this list. And then the incredible book that is Wise Child by Monica Furlong. (I could of course add some Dutch-language authors, but I'm limiting myself to books that are at least somewhat known in English or were originally written in English).

It's funny the author should mention an 11-year old reading War and Peace, as I believe I was either 11 or 12 when I read that book for the first and so far only time. And while it was interesting, and most certainly did not take a year or even a month, I'm tempted to say so much of it went over my head that it might not have been worth the effort at that point. But certainly, other classics like The Three Musketeers are doable at that age, even in unabridged version.

And yes, there seems to be kind of a lot of fantasy on that list... I haven't read many of those, so can't really say if they're unworthy of being on the list, but I do have suspicions in that direction, in the cases of books like The Spiderwick Chronicles or Percy Jackson and the Olympians. Those are recent books which have neither proven they can stand the test of time, nor (afaik) shown the kind of quality that turned Harry Potter and, perhaps more debatably, His Dark Materials into instant classics. Cornelia Funke's Inkheart was an interesting effort, and you have to love Funke for her impeccable taste in children's books as she proves with the opening quotes of her chapters, but I'm not sure the book or the trilogy was quite that memorable.