I agree with Paul that Microsoft needed to come out with this information sooner. And I also find it nice that Microsoft went this route with upgrading of the Windows 7 OS.
By no means, do I feel this was an "accident" by Microsoft. This installation method was designed this way on purpose and Microsoft clearly intended their customers to fully utilize it. This gets them a sale, plain and simple. People who might have otherwise pirated the copy if they had to pay the full install price, might be willing to pay for the upgrade. Even if they only persuade 20% to take them up on this, that's 20%.
Microsoft can and will sell this at any price to anybody. You got OEM, retail, upgrade, student, MSDN subs, Technet...all have wildly different pricing for the exact same thing. They take the money however they can get it.