"I think at least the app sandboxing makes a lot of sense. The more I hear about things like devices collaborating to spy on you or apps stealing data the more I want to be able to control which apps have access to certain data or which ones can activate e.g. the microphone."

But free programs won't do this (or can be made not to.) So it it just me or is this really only fixing a problem specific to the world of proprietary programs that people cannot change? (And in that case you should move to the land of the free rather than sandboxing said proprietary program.)