With so many to choose from. Apparently, as of May 04, it was decided to restore the original naming policy, whereby hero names you have are not in jeopardy of being taken by another character.
Originally, back in October, a new policy was enacted to free up name possibilities for City of Villains. Names for characters under level 35 on game accounts that have been inactive for over 90 days will be changed to unreserved status.
Now, however, there does not seem to be a need to support this, so they are rescinding this policy and restoring the sanctity of the names we generate for our heroes. They have done some research and found this isn't something that needs to be done now. Also we will receive a 30 days notice if this policy changes again.