I'd say the remaster is more aimed at the likes for me who have PS4 and never played the game on PS3 and are looking for some shiny stuff to play on the PS4.
Why didn't I get the PS3 version? Just never got around to it due to existing PS3 backlog and by the time it had been reduced, didn't see the point in getting a PS3 game, whereas I'll definitely buy the PS4 ver, probably day 1. 60fps is also big selling point for me. 1080p doesn't fuss me, buy 60fps will make for a much better experience than the PS3 version could have done.
There are also a lot of PS4 owners out there who never had a PS3 and so no access to the game originally.