What we want is power. In the desktop era, having source code gave us power, so we associated the two and demanded the former - but this obviously hasn't translated to the cloud.
You can't download a Facebook profile and then re-upload it somewhere else and still be connected to all your friends etc. That lock-in gives Facebook power over its users: proportional to how much they need what Facebook gatekeeps (e.g. "all the news about my grandkids is on there").
When I want to stop using something, but I can't, that's power someone holds over me. In my case, that's Google search, GMail, and Android. I actually hate the latter two, and I've tried leaving them all, but here I am. What they've got in common is that they're all protective layers over what I need to stay connected to the outside world despite being highly dysfunctional (i.e. discoverability on the web, email spam, and phone hardware).
Because of this, Google's got me in a way that - because of open source - Microsoft never could. Whatever comes after open source needs to address that power delta directly. We need choice, but also connection.