I haven't read evey post, but it seems that everyone has their own reasons for this. I don't know the reason. Maybe it was the low sales of the PS3 and SE got scared that it won't sell as much as they want, so they went multi plat. If this is the case then it's not MS fault.
I personally blame SE themselves. If they removed all the FMVs from the game, they can probably make the game 5 times longer instead of twice. Personlly I think FMVs are the reason for such HUGE useless data.