I think it needs some sort of actual progress or thing to work towards. It has this huge world and there's no incentive to go out and do anything with it.
>This is a story of how you died
Okay, I closed all the curtains and I'm standing in the corner of a house eating food and doing nothing. I win.
The game being a survival game with the idea of "You'll die, its just a matter of when" isn't a very fulfilling premise it feels like. Get tagged by a Zombie, run over.
What I think they should do is have events that progress and change things up, maybe Zombies don't respawn and instead new ones drift in, give you the feeling of actually clearing them out, have bandits start showing up after a while, and eventually military. Give something for the player to actually prepare for and get through. The game being designed around the whole "this is how you died" thing, while being grindy as fuck with all these skill levels is nonsense. If your character actually gets eaten or something, sure, but from the virus? Why not make it so you can actually beat the virus if you consume enough medication and treat the wound very well? Make it so when you get bit, your character now has something they have to fight for, a race against time to scavenge the stuff you need and make some risky moves for because its over if they don't.
Project Zomboid feels like its just a sandbox of Zombie related game ideas/concepts and not a fully focused game.