Brofessional

Nights need a little more ambient light. Most nights the moon is visible irl, and even without the moon visible there's starlight and sunlight scattered through the atmosphere, it's never pitch black. Or they could just add a very dim light-radius around your character that's only visible to you, akin to Diablo or Dark Souls. Just bright enough so you could see walls and trees directly in front of you, but still need a flashlight to loot effectively, and you wouldn't be able to see things in the distance well.

All you need is the ability for players to keep a small stash of items somwhere that can't be pillaged by other players. No more than say 50 slots for the highest tier stash. Bases and camps are nice, but they don't work when they're not guarded 24/7, and you can't establish any sort of player-organized factions to control different areas because your character isn't tied to the server. If you absolutely can't stomach there being 100% secure stashes, we could at least have buryable containers. Those would be very difficult for anyone else to find, and you could have buryable safes at the high end that require a combination or explosive to open. (maybe have the explosive damage the contents too)

This happened to me in the control tower at the NE airstrip. Pretty sure it wasn't just a sniper because I didn't hear any shots, just instant death while I was in my inventory menu.

The only thing they really need to fix is the instant-respawning zombies. You should be able to clear an area by force for a while and loot in relative safety. I was on a hill providing cover for my friend who was working his way into a factory, and when he would shoot one zombie in front of him with his MP5SD I could see the zombie instantly respawn less than 50ft away.