I feel like the Green Arrow that emerged in THE BRAVE AND THE BOLD 85, JUSTICE LEAGUE OF AMERICA 75 and GREEN LANTERN 76 was miles away from the Green Arrow before that. However, Green Arrow had lost his back-up feature in 1963 and was mostly just a supporting character in JUSTICE LEAGUE until those changes in 1969. So one could argue that they rescued him from obscurity.
And at least they never retconned away his previous adventures. The fact that he had been a spoiled rich guy who fashioned himself after Batman, but without all the angst, served as contrast for the new Oliver Queen that emerged. Losing all his money seemed to have an even worse effect on him than the loss of a loved one for other heroes. That he went so far the other direction in his beliefs seems like the zeal of the newly converted.
It was one of the most drastic changes in a character in comic books without a reboot.