Fishing ! is a really good nature hobby.
Far fetched but I feel like fitness could be broken down further: some sims are into boxing, others like rock climbing or martial art.
Handiness has a sorta sub category in sculpting, both wooden sculptures and pumpkin carving (clay isn't linked to handiness, but still fits. Although I wish we could bake the result and keep it forever).
Same with logic, could be interest in astronomy or chemistry, could be chess aficionado.
Skills covering broad subjects have several hobbies within them, and that helps me with making sims even more unique.
And not a skill (it's not dependant on herbalism I think ?) but one of my sims is really into entomology with Outdoor Retreat. Plus walking sticks make adorable pets for kids.
If only spawners weren't limited to Granite Falls. Making interesting gameplay niche is the surest way to ensure your players forget about it.