Population control, preventing overgrazing, stuff like that. However, the Netherlands (unlike most countries) is basically a big farm with practically no wild nature, so humans manage that stuff already. Maybe I'm exaggerating a tad, but I don't get what benefit wolves have in the Netherlands specifically.

The promise that the ecosystem would manage itself and wolves would just pick the least fit of the herd. It's shown they just like to kill for the thrill. There are cases of 30 sheeps per night in one site. 'Just Place fences' is a common heard thing, however wolves are smart and will just jump over or dig underneath. If you want to make a proper barrier with concrete is just practically unaffordable for the farmers.

To the average Dutchy? Not much. To the average European? Also not much. Animal preservation is well and good and all but anything wolves can do for the deer population humans can do. Though Idk how it is in NL, but wild boars are nasty fuckers and we do good to keep them down, so there might be some benefit there, though not sure if damage by boars if offset by damage by wolves.