I disagree. In fact, I agree with one Internet poster's remarks, in which he says,
You definitely get a different spin on the book after you have kids.
There's a reason the story's called The Giving Tree and not The Taking Boy. The tree, not the boy, is what the story is about. I think some folks lose sight of that because we're used to humans being the central characters in our stories. The boy is just a necessary element to tell the story of the tree. Focusing on him too much makes you lose sight of what the book is really about.
When I was younger, I remember feeling that the kid was just a greedy bastard and the tree was a total doormat and an idiot. Now, I have a kid, and I think I understand: the tree (metaphorical parent) is willing to give every bit of itself for the boy (metaphorical child). What makes the tree happy is being with the child, and there's nothing the boy can take from the tree that will decrease that happiness.
Before I became a dad, I always heard about parents who didn't have enough money to feed the whole family, so they'd go hungry and give everything they had to their child so she could eat. I never understood that. Now, I think I know why people would gladly suffer for their kids. She really does mean the world to me, and I would give every part of myself for her. And I'd be happy.