They don’t need a warrant to scoop anything up. They already are scooping it up. Then they want us to pretend they don’t listen. The truth is that they probably listen first and then ask for a warrant when they find something.
That tells me Obama felt someone would rat him out, so they got warrants to cover their actions.
That analysis makes sense. The ability to spy on us is not really new. What was revealed in the latest wikileaks is that CIA (and probably many other similar agencies all around the world) has tools to make a spying action appear to be the work of another government. They convinced Trump that Russia hacked Hillary’s server but I am nowhere near 100% convinced.