Since there are (far) more garments than base figures, and the garments have much greater freedom of shape variation (volume,  folds, dynamic effects) I expect there will probably be more demand for re-establishing vertex order in garments than in base figures.

In the UV domain there normally should not be any non-manifold edges so indeed jt would be an easier starting point. Also most used apps doing geometry alterations will not change the 2D representation. (It would be a good thing if they did, but that is another discussion.)

A good 2D representation in general is much more powerful and straight-forward. It would work even after complete remeshing, provided the shape and location of the uv islands is maintained. Maintaining continuity at edges/seams needs attention though.