I *believe* the lock screen only goes away when Security is set to "none", that is, no password, no PIN, no pattern, and no swipe.
Now that I have my phone re-configured after my reset, I have Tasker and Secure Settings set to continuously configure my phone in this mode. Whenever the screen sleeps, I swipe once or press the power button to wake it and my home screen appears.
For locking the phone, I have a Tasker shortcut task placed in the perpetually visible app bar on the bottom of the screen. Pressing this immediately locks my phone and requires a PIN to get back in. When I'm back in, Tasker resets the Security feature to "none". In addition to this, I created a Tasker timer app that locks the phone after 15 minutes in inactivity.
This is how the Lollipop lockscreen feature should work IMO.