"Likewise, I see no shame in writing Captain America or Wolverine"

In this quote, Mark Millar is revealing his belief that there is no embarassment in writing about popular comic book characters such as Captain America and Wolverine. He is acknowledging that some might view writing about these characters as less prestigious or artistic compared to creating original characters, but he sees no concern with it. Millar is likely protecting his own work and the work of other authors who have actually picked to discuss these renowned characters. He is stressing that writing about these characters ought to not be looked down upon and can still be an important and satisfying innovative undertaking.