I think you are totally wrong. If I came on here having ordered my machine in March after it had been shipping for 2.5 months as originally expected you would have said "You should have bought it sooner or waited.
Not at all, I'd have said the exact same thing I'm saying now - you're justified to expect some sort of compensation for the initial delay, but not for whatever changes the company may have made after you placed your order. What matters in that case is the date you ordered. If you had placed your order in March, you would've bought the specific computer they had on offer in March, while what was just launched is a new,
different product. In the hypothetical case you described, you should've been delivered the old version, which is the one you bought, with the possibility of claiming compensation for the delay, but not also for them bringing out a new product in the meantime.
BTW the 17" delay was not a shipping department error, it was a manufacturing problem, but either way some kind of compensation should be owed to someone willing to wait it out on behalf of a company they trust.
Compensation
is owed, but it's for their failure to deliver to you the service for which you payed. You bought their product, said to be delivered within a certain timeframe, and they failed to keep to that schedule. But that is the only aspect in which they have failed you, as a customer. Them bringing out a new product after you bought the one they had an offer at that time is not such a failure, because it's in no way part of your purchase. It's just bad luck on your side.
Look at it this way: take the instance(s) in which you consider that Apple have failed to provide the service you payed for, and tell us how your situation would've been different if they hadn't.
As far as I can see, the only way in which they've not lived up to contractual obligations is by not delivering on time. Continuing from this premise, if they hadn't screwed up, if they'd delivered on time, you'd still have the old version of the computer at its given price, with no claim to any sort of compensation, regardless of whether you had ordered it in February or just a day before the changes.