Generally, I'm suspicious of anyone proposing a list of books you must or should read. So I was naturally suspicious of this list. Nonetheless, in The Guardian putting together a list of books you should read, it was nice to see that they did include fantasy, even if they combined it with science fiction and horror.
Why am I suspicious of such lists? I'm not comfortable with the idea that there are books you should read... whether to be educated, entertained or anything else beginning with 'e'. It's too dictatorial. Besides, just reading Milton or Blake doesn't necessarily educate you. One could get quite as much education out of... ah... let's say Milne's Winnie-the-Pooh or Child's Charlie and Lola books. Being able to assert you've read such and such a book does not give you greater intelligence, mean you understood the book in the first place, or indicate that you have better taste than everyone else. It's simply a lazy short hand that has gained credibility.
Of course, it is sometimes amusing to create your own list of 'must-read' books. However, even though I have a doctorate, I have no desire to impose my list on any one else. Even in terms of coming up with reading for my subjects, I wish one day to come across a way to make it practical for everyone to read what they wish to. In the meantime, I just settle for trying to find some examples that may hopefully challenge preconceptions.
This is not to say that it isn't worth reading Milton or Blake, either. It is. Definitely.
And MacGavran wrote a brilliant essay about Blake's poetry and Calvin and Hobbes that I would recommend!