I think zombies respawning after a server restart would add a much more realistic feel to the game. For example, if you go into a little town and notice no zombies around, you get suspicious and your caution level goes up. You might think you're alone and it causes you to be more cautious with every action you do. So zombies respawning after a server restart would really be a good idea considering that people are complaining about zombies respawning right next to them and I totally agree with that.