DIC isn't regarded as a very substantial aspect of the GIJoe mythos in animated from. It's there, but its something I believe most cringe though. I actually watched some clips on you tube. I had forgotten just how bad it really was. Serpentor was a bit player in the Hama comic. 11 issues, didn't do much, then Zartan shot him. Bottom line, his popularity steams from other aspects of GIJoe media. Duke wouldn't be considered iconic if everything began and ended with Hama either.

Serpentor is most certainly one of the 25th most iconic characters.

Now if Hasbro would make the Sgt Slaughter (putting Fridge in that poll is an insult to the Sarge), then I really have respect for Hasbro as actually looking at the larger GIJoe mythos that exists and not just serving the whims of hardcore comic fans and collectors.