I will never buy a car with that feature unless I can turn it off. I don't need the be fighting my car if I need to swerve in an emergency situation.
Though I've rarely had it misbehave so I keep it on. If I lived somewhere with lots of narrow winding roads however, I'd probably reach for that button.
(I disagree with many modern car systems and think they make for worse drivers, but keeping you on-lane at high speeds is not a bad thing.)