Neither Stan Lee or Gerry Conway felt Gwen was boring? So if they didn't think she was boring why did they kill her off? If Gwen was such a bad character why did the fans wright hate mail to Gerry for killing her off in the first place, and if Mary Jane was so great why did Marvel recently decide to do the ever so lame "One More Day" story to break-up the marriage. The truth is the Hero should never get married, he sacrifices that part of his life to serve the greater good. When the only step left is to Mary off the hero, then it is time for that hero to be retired.
I wouldn't say the Hobgoblin was more interesting, but he was as interesting as the Green Goblin, at least until they fucked it all up by changing his story as far as his being Ned Leeds was concerned. Mary Jane was OK at first, but as things progressed it began to revolve around there relationship to much, and a good adventure became secondary. I really didn't care about Mary Jane by the time they got married, and she wasn't doing anything buy wining about the Spider-Man side of her husbands life. She became stagnant and in turn made Peter stagnant.
With the end of the silver age, came the end of strong plots and well developed characters. Wolverine and the Punisher are two of the worst characters ever conceived. They never change, or evolve, everything that happens simply rolls off them like water off a ducks back. Although when Garth Ennis writes Punnisher it is an entertaining read.