My original observation wasn't worded as well as it could have been. I meant in situations where hard braking could be required on a moment's notice for no particular reason (e.g. Chicago freeways where everyone is doing 70 mph bumper-to-bumper and decreases to 10 mph all of a sudden).

Indeed, when someone changes lanes in front of me, I gently let off the accelerator, but as someone else noticed, that can enrage drivers behind me (I don't take it personally), and I'm definitely traveling fast enough to remain in the middle lanes.