Answering to your second question first -- yes, you can apply tangent plane modifier to a profile callout.
As for advantages:
It better reflects "mating surface nature" of a considered surface. Since tangent plane is formed by 3 highest points, this is the plane that will most likely be orienting other parts placed on the considered surface in an assembly. Controlling parallelism (and indirectly flatness) of the entire surface, with all its irregularities, may not make too much sense in such case.
By placing a gage plate on the considered surface and probing it with a height gage or CMM for example. The quality of the gage plate is considered to be "almost perfect", so you will be very close to checking the tangent plane.
It means tangent plane modifier is used in applications when u dont want flatness control.Tangent plane modifier has concers with just high points and lower points are controlled by rule 1
