So, right now, the playlists are split in 4 parts, no-parties, parties, dlc1 and dlc2. There are 3 parties in this situation.

Naughty Dog. Arguably won't make much money off the DLC maps anyway anymore, other then that, free DLC maps on ps4 aren't really a system seller, whereas the 1080p60fps and free left behind are. There is noone who will choose the PS4 version over the PS3 version because the DLC maps are free, mainly because 99% buys the game for Single Player anyway.

DLC-owners. Have to cope with ridiculously long load times (SR ~5m, Survivors ~∞ and Interrogation ~10m). Next to that, the games often are way laggier then the games in no-parties and parties. Finally, most people playing these maps are either shotgun tryhards or corner campers, although usually a combination of both. The DLC-owners don't really get their money's worth. Next to that, me, as a DLC-owner I wouldn't be mad if others would get the maps for free whereas I had to pay for them.

Non-DLC-owners. They don't really have the right to have something if they didn't pay for it, however, in this case it would benefit all parties, as the player base might grow a little more if there is something new like this.