Do you practice applications for your own use? That is, not simply to be able to pass them on, or simply because you enjoy the kata and want to better understand it, but with a view to honing skills that you may have to use in a real-life violent situation.
If so do you find that any one kata has all the answers for you, or do you 'cherry pick' from the kata that you know to find those applications and principles that best suit you? Is there something that you have used successfully for real that you haven't yet found in a kata?
Assuming that no one single kata exactly fits your needs wouldn't it make sense to create your own kata? Mark Carroll, on one of his DVDs, states that, in his opinion, a kata is someone else's fighting system and that we should be training our own.
Just to be clear - I'm not suggesting abandoning the kata you know, or teaching 'your' kata to others. I'm simply putting forward the idea that, assuming that you're training for self-protection on some level, you get what you train and therefore you must be sure that what you're training will be of some use for you at need.