Exactly, and from what I recall, he did appear in both Disk Wars and Future Avengers, even had an arc in the latter about taking down Norman Osborn for mind-controlling the Hulk so he could make it look like the Avengers couldn't be trusted and superheroes as a whole needed to be regulated for the public good by the government, mostly so no one would interfere with him as the Green Goblin. Disk Wars also had him as a major supporting character in the first several episodes, and then later he showed up bonded with/possessed by the symbiote that would become Venom. I'm just saying, I'd like to see him have his own anime series.
Awesome design by Iban Coello there.