When have the Celtics actually asked Green to be a "#1 scorer"?
When they built a roster on which he's the best scorer.
Built?
Yeah, take a look at Danny's offseason works

I liked the Perk+Nate for Green+Nenad trade, Celtics won that trade and they would've won the title if the O'Neal brothers or Krstic (even Erden played well as an immature rookie) could've stayed healthy to play in the playoffs.
Green is a very good player, and I like how he's playing SG and still contributing to the team. His ballhandling is too poor to excel as a guard, but he's progressing in his defensive game. He's around Rondo's age, he can score and defend, creates some mismatches. He's not a star, he's not great... ok, but which players in the NBA are better than Green at his price tag? Not a lot.
Green isn't keeping the Celtics from being great or signing a star free agent. I really don't get all the hate, and trade deadline can't come soon enough.
Go Celtics!