Luckily, Google is righting the ship with Android 5.1 and bringing back the much-loved feature. Now you can ignore your friends and family in peace...
» Smarter notifications : Android 5.0 let you silence most, if not all, your notifications set for certain down times. Now, Google smartly implemented an "Until Next Alarm" option, so now you'll be able to keep people from disturbing you once you sent an alarm and you wake up or do whatever.
» No more crappy Wi-Fi : At public places like airports, restaurants, shopping malls etc, there's usually a public Wi-Fi signal that makes connecting to the internet a nightmare. Everytime you think you have a signal, you end up finding out that the free Wi-Fi network doesn't work.
Android 5.1 fixes the problem. Now, when you connect to one of these poor networks, your smartphone will remember this connection and won't auto-connect to it in the future. It's a little feature, but a great one.
» Safe browsing : In addition to making sure you never get an unwanted Wi-Fi network, Google may also be working on a VPN service so you can browse networks more securely. This is still in rumour-y territory, but Pocketables has discovered a new app tucked away in the All Apps folder called "Google Connection Services."
Considering this was discovered on a Nexus 6, supposedly the only device (at first) that will be compatible with Google's upcoming wireless service, it's possible that Google is waiting for service that to roll out first. Either way, super neat feature!
» Protection against thefts
Google is also upping its anti-theft game, at least for Nexus 6 and 9. According to Android Police, a new anti-theft feature would make it difficult for thieves to replace your account as a primary account; add any accounts of their own; and access the phone if they wipe the phone and try to login with their own credentials.
However, right now the rollout seems pretty restricted. Hopefully, Google will grace more smartphones with this feature in the future. Or at the very least, legacy Nexus devices.