This.. really isn't suprising. Ios 8 is immediately available on all modern iPhones, whereas Lollipop is still unsupported on almost all devices in the android market. Heck, the Verizon galaxy s5, one of the more common phones, just got the update yesterday! Additionally, many people are afraid of loosing their root, which is all-but-essental for power users.
The slow down of adoption of iOS updates is something that should worry Apple, and all developers invested in the Platform. That worries me…