OK, physical modelling is easier to tweak but it is rather like instead of buying a print of the Mona Lisa in a nice frame you are given a piece of canvas, some oil paints and a few bits of wood.
It is much more flexible but you need a special talent to make anything out of it.
Maybe one day it will be possible to acquire a physically modelled sound engine that will allow a configuration file to be applied that creates a given organ. It will take a lot of development to not sound artificial, though. It would also allow the flexibility to add any other stops you might want.
As someone who is interested in real organs I like the approach of sampling and Martin has made it sound as good as I need so I do not feel the need to explore anything else.
Regards,