I suggest to make server more cardcore. As you know mobs spawn only at night. So at daylight we can work in peace, do whatever we want and when it comes to night we gotta defend ourselves so badly. In my opinion that will increase interest in game. Because almost everyone has enchanted items, armor and it is easy to kill mobs. They are like chicken for us. I am not even afraid of zombies. When I see them I am like "pfff come here kid(s)". With "new incoming mode" game should be like:
1. Zombies will have more HP and it will be harder to kill them
2. Increase amount of spawned zombies around
3. Increase their damage. Like 1 zombie hit » goes 1 heart
That will force us to scare from zombies and be more careful at nights. In my opinion sounds cool.