He changed television.
He changed cop shows, and doing that, he changed television. Before he came along, the cop, lawyer, doctor, whatever shows were more formulaic. The issue came up, the star attacked it, and by the end of the show, it was resolved.
Hill Street Blues changed all that. The issues weren't as important as the people involved. Sure, you had your crimes to be solved, but the characters, their interactions, and their evolutions are what drew us in. Suddenly, the TV shows were not just neatly packaged boxes to be offered the viewer but a storyline that took place, episode to episode, season to season.
I didn't watch it much, and the episodes have faded. But the memory of the shift commander saying, "Let's be careful out there," the undercover cop with the onion sandwiches yelling "dirtbag!", and the police captain and female DA hooking up, remain. And I may not have those details right, but you get the picture.
We all hope to leave our mark before leaving this world. Mr. Bochco left his. Good on you, sport.