I honestly do not remember Apple ever promising to have Airdrop for iPad 3rd gen nor the iPad 4th gen when those devices came out, let alone ever once said anything about Airdrop until just recently, well when iOS 7 was announced. I also do not remember Apple calling me and telling me I need to purchase a 4th gen iPad in order to have this feature. There is some sort of difference in the hardware between the 3rd and 4th gen iPads, be it implementation of Bluetooth 4.0 or even the chipset in the device. There were some pretty big changes in the 4th gen iPad, e.g. The newer A6x vs the A5X, upgraded WiFi and Bluetooth antennae, and I believe an update on the RAM also. So something in there could be what has caused AirDrop to not be a feature of the 3rd gen, or maybe Apple plans on turning it for 3rd gen owners as soon as they work out the kinks with our hardware set?!? There really is a lot of work that goes in to making software of this magnitude, and sometimes the older hardware isn't compatible for whatever reason, or it isn't as efficient as Apple would like.
But before we all complain about a missing feature we should stop to consider why it was left out, and ask if we could have designed it better than Apple did, and if that is the case, why aren't we working for Apple instead of being consumers of their products?
I for one do not work for Apple, nor am I affiliated with them in anyway, but if you can do it better, get hired by them, or create a better product. Or since we are consumers, flip to Android, or Windows phone if you don't like what Apple offers, you may find something on the other side that you like better. It's a great thing to have choices, don't you think?
Now I was a little sad to think I can't test Airdrop, but what do I know about Apples thinking for certain features, and just moved on.