In the "news that will ease your OCD" category, Android "L" finally adds proper support for the battery percentage trick we were first made aware of in Android 4.4. Yes, you still have to download an app from XDA (or use a couple lines of ADB commands) from this post to get it working in the first place, but in the "L" release it no longer periodically disappears or decides not to work in certain situations.
And yes, it is remarkably, incredibly, unfathomably dumb that Google doesn't include this as an option in the settings menu by default. I can only imagine it's some nuanced philosophical argument about building a phone / OS that shouldn't have to show the user the battery % because it increases range anxiety, isn't perfectly accurate, and makes it seem like the battery is something you should always be watching, but that's reality. Android battery life is unpredictable, varies greatly from device to device (even Nexuses, which generally have had poor longevity), and for god's sake, even Apple has a battery percentage display toggle in iOS.
Let's hope this is a sign the feature will become user-facing by the time "L" goes official this fall.