I was really hoping they would bring back whatever API made it possible for things like AppOps Launcher to allow you to prevent other apps from accessing things like your contacts, account listing, or location. I was hoping that when they took it away it was because it was intended for release in a future version, but we've yet to see it since.
The problem with coarse-grained control like AppOps is that it can cause apps to malfunction or even outright crash when they try to use permissions that you revoked. This is probably not the kind of behavior that Google would like to enable for the average user.
Personally, I'd prefer a subtler (but possibly more draconian) approach, such as exposing a fake or empty contact list to apps that want my contacts; exposing some random location in the middle of nowhere to apps that want my location; and exposing a fake or empty folder to apps that want my pictures. Grant access to my messages, but never actually notify them when a new message comes in. Grant access to my microphone, but only ever feed them silence. Poor apps will not even suspect that anything is amiss! Is there any way right now to do something like this on rooted phones?
The problem with Android, being a meta-distribution, is that Google has less control over when users (not just Nexus) get version X of Android.
I remember Andy Rubin said Android could evolve more quickly because it was open source. Without debating that, its clear that in practice we haven't seen that when taking into account what users are actually using.
This makes it very difficult for Google to make these breaking kinds of changes to make things better, so entropy keeps accumulating in the platform.