We know there have been a lot of changes in Android 4.4, and a lot of them visual. One of the more obvious changes, which you can see in the image above, is that stock Android now features white status bar icons instead of blue. You mightn’t think that this means an awful lot, and you could be forgiven for thinking so, but to understand why this change matters, you need to understand how things were.

How it used to be

Previously, in Android 4.3 and for quite a few versions before, the status bar icons were blue. Sometimes they turned grey, and many people probably didn’t really know why that was. Put simply, a blue WiFi or Mobile Data indicator showed you that your Android had connectivity to Google services (and probably, the Internet as well), and a grey indicator showed that your Android couldn’t reach Google’s services. It probably would also indicate that you couldn’t reach the Internet, either, as Google’s servers are pretty reliable.

Previously, you would also have seen little up and down arrows rendered over the top of the WiFi or Mobile Data indicators, to show that data was moving. Somewhat useful if you wanted to see what your phone was doing, but otherwise, probably not all that essential.

How it is now

In Android 4.4 KitKat, this colour changing behaviour is gone. The indicators are white, and they’re white regardless of whether your Internet connectivity is active, working, or not. According to Android engineer Dan Sandler, these white icons were chosen to present a more neutral palette that works better with apps. Equally, on a transparent status bar, white and grey icons are a lot easier to see and make out than the previous ‘holo’ blue.

To determine whether your Android has a connectivity issue, you need only swipe to the Quick Settings drop-down. Your WiFI or Mobile Data indicator will be white if everything is working normally, and a muted orange tone if there’s an issue with connectivity.

Data flow indicators have also been removed from the main status bar, and also appear in Quick Settings now. Why have they been moved? The answer is fairly logical — these data flow indicators take a noticeable amount of CPU and GPU time to render, and so moving them away from the primary status interface saves resources and allows your phone to either use less power, or offer more power to other more desirable tasks (such as running your apps or games faster).

What Dan Sandler said

On his Google+ page, Dan Sandler explained these changes in his own words, which you might like to read:

Seems like this is as good a place as any to explain the changes to the system status icon colors in KK.

1. Whiten ALL the status bar icons! 

Aesthetic concerns definitely factored into this (as has been mentioned elsewhere, a more neutral SystemUI allows apps to manage their own color palettes a bit better), but also keep in mind that with the new translucent bars feature, the color became a usability problem. Good old 33b5e5 doesn’t pop as well on top of random wallpapers, even with the background protection.

2. What about the MCS GCM indicator? 

+Liam Spradlin basically called it: “Overall, network connectivity has been made strangely more opaque in KitKat, though for many average users this isn’t a huge concern.” In fact,most users find the colors confusing, if they notice them at all. Even the vanishingly small fraction of users who understood what the gray meant only really looked for it when things weren’t working right; now you and I just have to remember to actually pop into quick settings to look for things like GCM liveness (orange is the new gray) and in/out indicators. Which brings me to…

3. B—BUT MY BLINKENLIGHTS?! 

So this (the removal of the little in/out data traffic arrows from the RSSI) was mostly a performance consideration, believe it or not. The way the data bits are bubbled up and drawn was not only causing a ton of extra rendering work, but actually forcing a layout (!) in the status bar as well. We could have more aggressively cached the bitmaps (rather than creating new BitmapDrawables from resource IDs every time, which was causing the relayout) but that would still have left all the drawing—multiple times per second in some cases—sucking away precious CPU and GPU from your game or Launcher animations or whatever. In the end it seemed like a lot of work (and battery) for what was effectively visual noise, so this too was booted to Quick Settings where it would be available for us nerds.
Dan Sandler, Google Engineer

So there you have it folks, the change from holo blue to white wasn’t just a random design change; there’s solid reasoning behind it, and Android 4.4 should be all the more efficient because of it.