At the end of a working day, when arriving home, after playing with our baby son, I put my iPhone on its QI charger and sit down in the sofa with my iPad. Annoyingly, when an e-mail arrive, a whole symphony of notification sounds is heard throughout the appartement coming from multiple devices. It's classic Notification Center behavior.
Imagine a version of the notification center where iCloud knows I'm currently using the iPad actively, so it doesn't let the other devices make any sound or light up when they receive a notification.
Or, after I decide to open a few of these notifications on my iPad and ignore the rest, I open up my Mac. On the desktop it shows me only those notifications I ignored on the iPad. What's already been seen, is gone.
Even better: when I leave the house I put my iPhone in my pants' pocket. It, together with the Apple Watch knows I'm walking outside of the house, and a newly received email makes only the Watch tap on my wrist. While my iPad at home stays silent and doesn't bother my wife while she's at home.
Wouldn't that be a better way of handling notifications? Things like being actively in use, the fact that a device is awake or asleep, wither it's moving or not, would define what an active device is. And only that device alerts me of an incoming notification. And if I act upon a notification on one device then it disappears on every other device.
And while we're at it: Developers, if I open your app: do clear all existing notifications.