I've only just got back and read this thread. Ironically I was in Cyprus visiting Russell Stutely and comparing 'waveforms' and 'rooting' and 'pushing'on different planes to what we do in my 8 principles and tai chi.
We all have an inside and outside, therefore I would have thought that any good student of the MA from any age will have studied both aspects in their own way.
In my karate I teach the internal system in sanchin, how to float the waist from that and the '5 animal hands' in tensho and 'power sourcing' in naihanchi. The system forms Chinto and Kushanku then contain all these skills. The internal connection and power sourcing is what really empowers karate and require no dramatic outward changes but for many a lot of 'softening', 'loosening' and sensitivity training is required. We 'push hands' on most karate techniques enhancing those skills on the touch reflex.
The work I did with Russell over the last few days was quite dramatic. We discovered that I could negate anything from the pressure points to the locks and waveforms and return the energy using my tai chi training. Adding his knowledge of PP's and joint manipulation to those that I had in the tai chi form increased the effectiveness. It was almost like we had both the 'poison' and the 'antidote'.
I don't think these skills were necessarily 'lost' as the kata contain the skills for anyone who looks hard enough and I have found others who made the same discoveries. I think it simply requires a certain kind of mind that will test and challenge everything, those who have seem to have come to similar conclusions.
The results were profound enough for Russell to uproot from Cyprus and return to England in the new year so that we are able to continue with our research. Meanwhile we have arranged a series of visits inbetween.
Sometimes you have to look outside your own system to find aspects accentuated elsewhere to discover what is actually hidden deep inside of your own. Therefore if a lineage of instructors have been externally stimulated - it might pay to research the internal aspects.
Hope this helps