@dik,
IMO I don't think the supplemental reinforcement can be said to reduce the ldh for a "standard hook" since ldh is a defined constant. But if you are using some modified configuration that includes supplemental reinforcement then I certainly agree than a "standard hook" should not always be necessary in order to obtain a reduced "lead in" as it was called.
We do this sort of thing all the time in anchor bolt design when Appendix D is not suitable for anchorage in small piers. The codes/standards should not prevent an engineer from using alternate rational methods such as strut and tie, etc.