That's why I avoid myself from being level 30. The DZ most of the time will be empty and even if you meet someone else, they're most likely people who want to farm just like you.
Level 30 is the bottom of the pipe. It's where all the shit get clogged.
And yeah, they should have just made PvE map filled with DZ-style enemies, loots, and chests for people who have reached 30 and finished all missions and side missions. Make a bracket so people can't power level their under-leveled friends in this new PvE map.
Btw, I'm planning to just replay mission on Hard and Challenging when me and my friend turned 30. I don't know about my friend, but if I found by that time that doing PvE missions isn't worth anywhere better than DZ, then I guess I'll just simply drop the game. lol