Think about this a bit, depending on how far you wish to go back, none of us are worthy to study karate. We are not of the correct group. Karate was not something shared openly.
Of course karate probably has always evolved to face the shape that the instructors needed to address. There were really no rules as what could change, jus those instructors choose to follow.
Introduce karate to the young.
Choose to share karate within the Japanese University systems.
Choose to share karate within the Naval War College.
Choose to share karate with the occupying forces in return for money.
Choose to share karate with the world.
Accept changes to what karate means.
And so forth.
A case can be made that karate has always been flexible. Some like it so, others choose to not make changes.
That karate has become flexible within the current society, is just another movement of an art that has been changing for quite some time.
To suggest otherwise, you might as try to hold a river in your hands.
Choose wisely. It always is the others who have made the wrong decisions.