Yes, and no ....
I'll go along with the logic that AT&T, by no means, should be COMPELLED to cut people some sort of special break on the contract terms, just because they want to move from the gen. 1 iPhone to the gen. 2 model.
But it's ALSO reasonable to suggest the POSSIBILITY that they'd do such a thing, knowing that it's good for customer retention and goodwill. It's also, theoretically, a beneficial move for AT&T *if* they have a long-term plan of phasing out the EDGE network and getting all their users on 3G instead.
(Sprint is struggling with a similar issue right now. They bought out Nextel, but they're now stuck supporting BOTH incompatible networks simultaneously. They'd love nothing more than to migrate all their Nextel customers over to new phones that run on the Sprint network -- except Nextel's "push to talk" walkie-talkie capability happens to work far better than the variation built on Sprint's own network. Therefore, they've started pushing the "dual mode" Motorola phones that can use Nextel's push-to-talk network, but Sprint's network for everything else. It's a big mess for them, actually.)
I fail to understand why you think you should get special treatment simply because you bought the first gen, you had that choice, you made that choice, you signed the contract. That's the whole purpose of a contract is it not?
I can appreciate you should be allowed to buy the new iPhone (full price) and insert your existing sim card and continue your contract, but I cannot for the life of me see how you feel you should get a reduction in price. Cake and eat it?