The new way that DMC4 is being created is for newcomers of the series, that's one of the main reasons why Nero is the playable character and not Dante, it's like a new start so playing the original three are not necessary. And even saying that DMC doesn't really have what you call a deep plot so there isn't really much that 360 players will have to know.
I'm really interested to hear about why you feel that the 360 doesn't 'deserve' FFXIII though, a bit of a selfish comment don't you think?