I think they're handing out upgrades to OEM's (eg HP, Dell, Sony, Acer) first, because those computers have the serial number written into the BIOS. I assembled my system myself and have a OEM Win 7 Ultimate License, but it's not a branded one, so it's still "we'll let you know what it's available" too.
I'm not opposed to just outright buying a new license should I build a new system, but I can't justify building a new system that will only be 10% faster then the existing one. (Mines the i7-4770 non-K, the only thing faster is a i7-4790k, the Intel Core i7-5930K is actually 20% slower per core despite having 2 more cores)