I agree. No obligation on Apple's part, but still it'd be better PR considering how much money is spent on advertising.3) I don't think that any thinks that Apple is OBLIGATED to give away this update. I do think, however, that most people agree that it was a terrible decision not to, and the good will they will lose over this is worth far more than any profit they will realize.
They probably could have paid $20 for every current touch owner (call it 2m, so $40m) out of an advertising budget calling it "promotion for customer good will" and not missed it at if they HAD to please the accountants.
On the other hand, one can think of it as iPod touch price reduction by $20, (which is a bit early by Apple's standards, but still...) with the catch that new customers are forced to buy the bundle of touch and the apps.