I don't know. I may be suffering from sample bias, but around me, everyone who have iPads and iPhone change models as soon as one comes out. And they feel an URGE to do it. For reasons I cannot understand.

I've also heard the same story from other friends in different places, so I can only assume that a large amount of pre-iPad owners seem to buy a new one systematically. I don't have market research data to prove anything, however.

The new one is better. Faster processor, better screen, more RAM, etc. Not too hard to figure out why people upgrade.

The devices aren't disposable, either. They hold value, and it's easy enough to sell the old one. Nobody is throwing away an iPad.

The URGE to get a new one is irrational. We dont see that on PC when a new graphic card comes out or something. The iPad replacement pace is massive and hysterical.

Why is it hysterical or irrational? The new model provides significant advantages to the consumer.

It costs about as much as a fancy new video card, and is much easier for users to replace than a video card. Plus, they can sell the old one, or hand it down to spous/kids/etc.