I was a little thrown off when the silent mode disappeared from Lollipop 5.0, but quickly got used to Priority Notifications and found it was useful during sleep mode. Sideloaded the 5.1 OTA update on my Nexus 5 over the weekend, and was awoken in the middle of the night to a flashing light, because the notification light has been added back into the priority mode setting. I guess some people wanted it back, and I could understand those that want that notification under certain circumstances. However, I would think that it would be easy to add that option into the priority mode settings, so that each user could decide whether they want it or not.