Why doesn't MBA mid-2011 support Continuity/Handoff/"New" AirDrop?

Hi!

I'm not trying to be stupid or anything, I know pre-2012 Mac's are not on the approved list etc., but I just need to know; Why isn't my MBA mid-2011 on the supported list for these new functions? Whenever I have to send something to my wife's MBA mid-2012, SHE has to click "support old AirDrop", which I guess is just a manual way to change protocol, so her Mac supports my "old" Mac, even though both are at Yosemite.

I get that there has been a sudden protocol change, requiring Bluetooth 4.0 (LE) and therefore resulting in two different systems. My MBP late-2011 doesn't have Bluetooth 4.0, and of course doesn't work, but my MBA mid-2011 DOES have Bluetooth 4.0! It should be supported, and WAS under the early test-versions of Yosemite. A simple patch can fix it as well, but it's introducing a security issue related to kext-signing, which I don't like.

It should also support the new AirDrop protocol as well, so that it would actually work with iOS also, I mean it has the hardware!

So I'll probably don't get an official answer, but I really don't understand why it's left outside the supported Mac's, when it actually does have the hardware. AFAIK the Mac Mini from the same time should also have BT 4.0 (LE).

Comments?