Because, at that size and price, I expect a computer. And thus, I can't by it. Because of this little chain of logic.
If a computer doesn't have a fully functional web browser, it's not worth buying.
A fully functional web browser needs to support Flash.
The iPad does not support Flash.
Now, I don't care whether Flash is good or devilspawn and whether so much stuff (games, Hulu, etc) should be running on it. The fact is that Flash is a big thing, and I want the things it runs.
But I love my new iMac, and it's not even broken, so Apple is still OK by me. It's just that they seem to think bigger iPod Touches are the future of computing, and no, I don't think so. Versatility makes technology complicated, but it also makes it awesome.