In taiji we say that you study movement in feet, then inches, then hundredths of an inch, then thousandths of an inch and then hundredths of a thousandth of an inch.
As we layer in the principles and subsequent skills we find that it's more about principles than techniques - it's more about your ability to maintain your centre, root, structure, mindset, breathing and then disrupt any one of those in your opponent to make whatever you do effective. Being able to 'hide' your centre from your opponent, locate theirs and disrupt it takes a lot of solitary form practice and then test it in application.
Techniques quickly gives way to principles, the problem I see with a lot of 'bunkai' practiced is that the opponent is still compliant - and although quite ingenious, is still unlikely to work agains a fighting opponent.
Even looking at the 'deadly' applications, if the practitioner doesn't have the above principles in place and the opponent does, it won't work.
Therefore I see kata as a trininity:
1. Health (mental and physical) good health entails getting posture, breathing, mindset, internal system, good centering etc..
2. Skills - the ability to disrupt a moving fighting opponent.
3. Application - breaking each movement down into tiny pieces to examine the grappling (seperating muscle and tendon from bone, stopping the flow of blood, air and energy), locking, throwing, dislocating, striking and blocking uses of each part of a movement.
Kata can be an excellent way of practice if you can practice your MA deep enough. If you only look at the surface technique and try to apply it without those hours of solitary and paired practice to understand where the physical and mental power comes from, you can only be skimming the surface.
When I look at the body language of even the 'experts' who commercially package their bunkai, I ask myself are they convinced that it would work or is it just a clever commercial mind making a sows ear out of a silk purse?