I can identify three fairly significant issues at fault here, all stemming from the fact that the original senseis actually fought and most of their successors don't:

• Many martial arts-- despite originally being optimized for keeping you alive in combat-- have since been optimized for being accessible and easy to learn, in some cases for preteens. Accessibility and effectiveness are in many cases at cross purposes.

• Many martial arts, without actual combat to point to as a metric of success or failure, have instituted systems of "point sparring" and so on in order to run tournaments. Thanks to Goodhart's Law, many of these martial arts have then become diluted by techniques and training optimized for scoring points in tournaments rather than defending yourself.

• Many techniques that were once very practical are no longer so, and out of respect for tradition or simple lack of constant reevaluation are still being taught.

  For instance, many traditional martial arts focus a lot on defending yourself against wrist grabs. I am told that this is because hundreds of years ago in Japan, wrist grabs were actually a common means of attack and important to know how to protect yourself against-- if someone walked up to you and grabbed your wrist, you couldn't draw your sword, which often meant you were about to die.

  Nowadays, of course, people don't often initiate attacks by walking up and grabbing your wrist, so there is much less utility in such movements, but the curriculum of many traditional martial arts has not been updated to compensate.