There should be a middle ground between FSD and manual steering. I'll call it 'Nudge Mode". In this mode, you steer and drive just like manual driving, but the car is ever so slightly trying to keep you in lane. If you steer out of your lane, the car doesn't fight you, it just exerts a tiny amount of drag to hold the lane. You can easily overcome this force and steer where you like, and there is no alarm or mode change when you overrule auto-steering. The lane retention force is small enough to be not (or maybe barely) noticeable, but if you do nothing the car stays in lane.