"we do not, and could not, go browsing at will through the lives of innocent people".
That is exactly what they do, using computers to automatically run through every email sent and website visited looking for "suspicious" patterns and trends. Spy caught lying to people, what a surprise.
"We use these tools within a framework of strict safeguards and rigorous oversight, but without them we would not be able to keep the country safe."
You will never be able to keep the country safe, accept that fact right now. Even if everyone was microchipped and had built in mics and cameras that these spies could access at will, people would still be able to carry out terrorism. So while accepting that we can never be completely safe no matter how much power we give the spies, it becomes a matter of just how much power we are happy for them to have over us, while still not giving us any benefit in being safe.
"an increasing proportion of such communications are now beyond our reach"
Which is good news, we SHOULD have communications that are beyond the reach of the government. How else could we freely talk about dissent and opposition politics if we were worried that the government could be snooping on us at any time? They come out with all this stuff about safeguards but that's shite tbh, I've read about how common it is at the American NSA for analysts to be checking their partners emails and phonecalls. Not forgetting that when people know they MIGHT be being watched at any time, they self censor which is bad for democracy.