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.

Its larger animal control.

Wildboars can be quite destructive, as are deers. the wolve was the natural preditor of those animals so the only thing that kept them in check was either hunting, disease or food availability.

In the UK deer over population is a problem for forestry as they eat saplings. So we spend a lot of cash hunting them (good food source, but not widely distributed in shops) Wolves stop that.

For the netherlands sspecifically, where there are deer they eat the trees that provide bank stability (ie willows) Less of a problem now but they also eat the pioneer species that were used to build polders.

Deer carry disease for cattle and sheep as well. although cows in holland are fairly hemmed in, ticks and fleas are less so.