I can't see how it is a loophole.
Lots of people with no intention of upgrading to windows 8?
They just got a whole bunch of people, that had JUST bought their full-priced copies of windows 7 to pay an extra $15 direct to them.....
And for the "loophole" people, that hadn't bought their PC's in the last 6 months, and probably had absolutely no intention of handing money to M$ in the next 2 1/2 years anyway, have now handed Microsoft extra $15 to upgrade to windows 8.
Why would anyone actually consider this as a failure?
Noting that the $15 upgrade (without checking) is a download only copy, and microsot really has no additional costs associated with these purchases, and now with all these "trojan" copies of windows 8 abounding, acceptance of the hideous metro interface will become mainstream amonst geeks, that actually hate the metro interface.
It's like Sony, Bluray & the PS3 all over again.