The mission of Wikimedia is to generate "neutral educational content under a free content license". The Foundation's resolution from March 2007 states that EDP use must be minimal, within narrow limits.
Subsequent to the resolution being passed, a number of efforts were undertaken to limit fair use usage on en.wikipedia. This affected discographies, episode lists, and character lists. A *huge* number of debates erupted over these removals. One such debate was covered at http://en.wikipedia.org/wiki/Wikipedia:Wikipedia_Signpost/2007-05-07/Fair_us.... The disputes have never ended. For discographies and episode lists, the debate has simmered down for the most part, with occasional flare ups. For character lists, the debate is still raging.
What has been the rule of thumb in removing the images is that an image of the character being used for depiction of that character only is allowable on that character's particular article, but not on articles collecting multiple characters into a single article. The rationale here is that if a character is notable enough for an article, they're notable enough for an image, and vice versa. Allowances have been made for "cast" type images showing multiple characters in a single image from the copyright holder (not montages made by editors).
Nevertheless, the debate has raged endlessly, and has recently exploded. It stands now on a precipice, and it is highly likely that fair use inclusionists will 'win' in that per-character images are going to be permitted on character articles (for example, see http://en.wikipedia.org/wiki/Hogwarts_students ).
Some discussion exists currently at http://en.wikipedia.org/wiki/Wikipedia:Administrators%27_noticeboard#Fair_us... and scattered through a variety of sections of http://en.wikipedia.org/wiki/Wikipedia_talk:Non-free_content
If Wikipedia is truly a free content encyclopedia, if you truly care about free content, we must limit fair use usage per the Foundation's resolution. As it stands now, this debate is lost in favor of people who are more focused on whether something is suitable as a guide than focused on being a free content resource.
A strong voice from the Foundation would be appreciated, most especially in favor of a new section added to clarify the local EDP at the second paragraph of this version of the guideline: http://en.wikipedia.org/w/index.php?title=Wikipedia:Non-free_content&old... (paragraph since removed in an edit war)
Thank you, Hammersoft