In addition to what was said about Marvel's current royalties program, the creators of Agents of SHIELD would rather get the royalties check by creating their own characters than give a check to some guy who worked for Marvel decades ago.
I wonder what the royalty check would be for a TV writer who gets their creation picked to be a part of the Marvel comic world?
I doubt any character created for the show will end up in the comics. I only see Agents of SHIELD lasting upto 3 seasons, with season 3 being like 13 episodes or it turns into a 13 episode series which runs for abit longer and that ain't bad.
The Disgruntled Greek