Animal nodes shifting makes sense, especially because they're important for end game quality cap. But I think we can all agree this increases the workload on hunters. Finding new nodes takes time.
Herbs and foraging in general have lost a lot of power over time and are at this point mostly marginal utility. That utility doesn't outweigh the cost of having to find new nodes constantly.
I think herbs should be completely static nodes, they just aren't powerful enough to warrant hunting node peaks multiple times.