It seems like everyone is making smartphone screens more useful when they're off, and LG's attempt is called Knock Code. This feature lets you securely wake and unlock the device with a series of taps on the screen while the phone is asleep. No need to buy a new phone, though. Knock Code is rolling out the the AT&T LG G2 via an OTA update right now.
Knock Code basically splits the screen into quadrants, allowing you to set a pattern of taps that will automatically wake up the device and bypass the standard lock screen. Neat, right? The OTA also includes some improvements to calendar/Exchange Active Sync, but be honest, you don't care about that.
The update (version D80020u) requires WiFi and should reach all devices soon. AT&T also seems to indicate you can check for updates in the system settings to pull down the update.