The bodies outside Parliament are barely cold...
And their deaths are already being used to justify going after end-to-end encryption. Never mind that dictatorships around the world will use that to ID thought criminals and send them off for re-education/forced labor/a date with a firing squad. Never mind that working encryption is what allows you to talk about your personal and government business with dramatically higher safety. Never mind that working, not-backdoored encryption is embedded in many payment card industry and financial industry regulations.
Let's just trash all that so we can find out if some guy with a history of violence might try as a matter of convenience to attach himself to jihadism, and kill 3 innocent people in the process. And that's assuming that Mr. Masood was not texting about kitten videos or soccer scores before he went off the deep end.