The whole Bobba Fett thing has always been a mistery to me. When I watched the original trilogy for the first time, I didn't even care for him, and for my total surprise, he was a very popular character. I still can't understand exactly why. Maybe it was because of the mistery surrounding him.

About his date of creation, I've managed to get some information and I think I figured it out. His armor was a rejected early Darth Vader concept, which had the Lord of the Sith as a bounty hunter, for some weird reason. When Star Wars became a huge hit, plans for a sequel started, and one of the first characters that came up for ESB was Bobba, pretty much from the original DV concept. Since he was created so soon, he was able to make his first appearence in a 1978 cartoon, in the HS. His character was not well defined, tough, as I belive he actually helped Luke on that cartoon.

Maybe that's why he's so popular, because he was available to the audience so early that they created some sort of expectation for the character.