Getting back to the original question. I think that "where" a form derived from helps answer the questions of bunkai and where that stems from. For example, in the japanese styles, such as Shotokan, not a lot of bunkai was passed on other than the block/punch/kick variety. Their emphasis was more on kihon practice and kumite, the view of many was that kata was just a way to practice the kihon. So, I think that many Shotokan stylists may have "reverse engineered" their kata to look at Shorin-Ryu applications for certain movements of the same kata or came up with meanings for the movements that worked for them (whether or not it is close to the original).
This is the main crux between eccletic and traditional studies. A more modern approach doesn't care where the info came from as long as it works; A traditional approach many times will disregard something because it's not from what their instructor/master said it was. Just using Mr. Abernathy as an example; his approach works and fits within the patterns of the katas he trains it with, to many that is all that matters. They have an effective means of self-defense and a way to practice it through the kata. Others will disregard that approach because it didn't come from the head of their organization or they were told that there were no grappling applications in kata, so they will ignore the applications in favor of a more basic approach of kicking and punching.