Apple is balancing ease of use with security here. Before touch ID many people didn't use pass codes and therefore had no security on their iPhones. Touch ID goes a LONG way toward ease of use while providing a high level of security. Considering the amount of personal information the average user has on their iPhone its not a great idea to disable Touch ID and passcode altogether.
To improve the utility of the lock screen iOS has evolved to include notifications, the today summary, quick camera access, and control centre without having to unlock the iPhone. All of these features allow you to quickly access information and repetitive tasks without needing to unlock.
I know it might seem like a nice idea to power on the display right to the home screen its just not a good idea to defeat the inherent security the lock screen provides.