When you have adaptive cruise-control which keeps constant distance with the vehicle in front of you by adjusting speed, you start to pay less attention to the road in general. You basically can't hit the car in front of you, so you subconsciously start to care less. So there are small curves of the road that fall under your consciousness' "radar" and lane assist actually helps in those cases.

But boy, how afraid I am when it triggers in the construction zones!

The reason for lane departure assist ( that’s the one that will be mandatory, not lane keeping on CC) is something else: inadvertent drifting off the lane when tired and driving without CC/autopilot/whatever (when you arguably shouldn’t be driving bad should have stopped, but sometimes you can’t, or don’t evaluate your tiredness correctly).