It more or less proves (to me at least) that the government(s) and the various secret services have absolutely no idea who to monitor specifically. So instead of targeting their operations they want to monitor all of us, just in case something of interest pops out that then allows them to focus their attention.
It's a pretty scary thought: just imagine, all that money, all those resources and still they can't do anything other than to put their ear to the ground and hope that someone messes up in plaintext so they can then try to backtrack and see what they might have missed.
In all these attacks it never happened that everybody was under the radar. Always one or more of the attackers that were technically known or even already under surveillance. And yet the attacks happened anyway. Too many targets make for a very thinly deployed service, which then has to be automated to make it work at all.
It's a pretty sobering thought, it also suggests via yet another route that mass surveillance is indeed meant to attempt to 'keep us safe', and that it fails miserably. The road to hell is paved with the best of intentions.
Terrorists have it so easy, all they need to do is to be just a little bit unpredictable or simply old-fashioned (in person) and there won't be anything whatsoever that we can concretely do to stop them. The only thing that actually gives a bunch of actionable data is when an attack is executed or when an attack goes sour (or rather: sweet as in, it does not work) from which direct evidence of contacts or plans is gained. This will then lead to a relatively short lived number of arrests clustered around the people caught or implicated and then it burns out again where the data ends.
And so then we get to wait for the next attack...