I take it you haven't read about this.
A large amout of PS4 purchasers did not own a PS3, this is mainly aimed at them.
Left Behind was produced after release. So could not have been included.
ND used it to develop their PS4 tools. So what if it is a reskin, it is still one of the best games ever.
I was playing Left Behind last night, on hard, on the PS3.