While I do not know exactly why that became the standard intro, I can verify that when I did open tourneys in the 1980's and 90's, that was exactly how I was taught to address the judges.

I always thought it was dumb to announce your school and instructor, too. Many judges who may have given you a fair score would hear you're from Master XYZ's school, and think "Oh! I hate that ba$tard! I'm going to low-ball his student's score here! TEE HEE!" Politics.

Like you said, just announce the kata and go.
"In case you ever wondered what it's like to be knocked out, it's like waking up from a nightmare only to discover it wasn't a dream." -Forrest Griffin