Quote from animephreak
Well, wasn't it not only half-bloods, but undesirables as well? Hence Masaki losing her powers, which lead to her death. Also Ryuken pretty much declared "I AM the last Quincy", meaning that all the others may have lost their powers, as only his family and the Kurosaki family were still pure ...
All mixed-blood should have died on that day, Uryuu was the only who survived and didn't lose his power.
Ichigo and his sisters didn't died because their powers weren't awaken I suppose.