This is a tough one for anyone born after 1960.
That said, it must have been indescribably gratifying for Sendak to know that an entire generation (and then their kids, etc.) read –and loved– his work. I mean we talk about wanting to leave a mark on the world; Sendak most definitely did that. To do so and leave the world happier and more imaginative than it would otherwise have been? That is downright heroic.