Its all about context and intentions...
Films and other traditional media that have graphic depictions or descriptions of violence, rape etc. are expected to do so within a responsible context.
e.g. 'Baddies' in a crime drama do bad things, but it is made clear throughout that this behavior is unacceptable. In cases where the 'goodies' use violence, there is usually some attempt at justification for these actions, and often some sort of remorse, guilt or notion that it is not a pleasurable experience...
Some, movies get into ambiguous territory, but usually the use some sort of tactic to make the situation acceptable for the intended audience e.g. some would say that Kill Bill gets away with gratuitous violence because it uses it in a highly stylized almost cartoon manner with continual canonical references (of course many people consider these films to be in very poor taste)
Most Games OTOH that contain violence make no attempt whatsoever to provide a meaningful context for the violence they contain - it is in many cases the only point! To make things worse, they tend to strive for as realistic believable looking visuals as possible (rather than stylized). In general, either there is no attempt at providing any reference points to how society as a whole 'feels' about the activities depicted, or the attempts made are token, poorly conceived and therefor valueless (A bit like the plot in a porno movie).
If/when games do provide responsible believable context and a philosophically and morally mature 'player' experience, then they will be able to 'get away' with more explicit and horrific content before being censored (IMO of course).