iOS 8 Adoption Rate Is Now At 73%

According to Apple’s own data,  iOS 8 adoption rate is now at 73% iOS 7 is of course behind at 24%, and 3% of devices are running a software version that 2 or more years old. For comparison, iOS 7 was installed on 80% of devices at the same time last year. What is it about iOS 8 that’s making people not updating ?