Back when Android 4.3 launched, users were excited to find a somewhat buried feature that allowed them to manage permissions for the apps they had installed on their phone. It was called App Ops, and the fact that it was included in Android 4.3 suggested that Google was going to give users some power when it came to what an app was able to do with their phone. However, that kind of functionality didn't hang around for long, as it was even more buried in Android 4.4 and has gone missing entirely in Android 4.4.2.
Sadly, it turns out that App Ops was never meant for end users to begin with. Dianne Hackborn - an employee at Google's Android division - explained as much when Google Plus user Danny Holyoake pointed out that such functionality was missing. According to her, the App Ops UI was there for development purposes and wasn't intended to be an end-user interface. That explains why it was so difficult to find at first, and why it's slowly been disappearing over successive iterations of the Android OS.
There might be a light at the end of the tunnel, though, as Hackborn says it could one day be rolled out as a third-party tool. Of course, such an implementation would probably be a ways off, and considering the fact that Google never intended us to see App Ops in the first place, we may never see functionality like this again. In short: maybe you'll get App Ops again later on down the road, but it wouldn't be the best idea to count on it.
It's a shame that App Ops has gone missing, but if it was never meant to be an end-user tool, we can't exactly blame Google for doing away with it in Android 4.4.2. Still, a lot of Android users out there have a problem with all of the permissions many apps request when they're first installed, and there really isn't any way to deny some permissions if you actually want to use the app. The realization of App Ops was certainly an exciting one, but now, it unfortunately looks like the party's over.