Personally not a fan of them. In my own maps, I usually worry they can be immersion-breaking (roleplaying as a zebra would be awkward if theres already zebra meshes yknow?). Tends to interfere with roleplays and such ("oh no the drought has forced all the herds away!!" *herd of stiff wildebeest meshes is standing two feet away*) so I like to just leave them out.
Animated particles can be kinda hit or miss for me, if they don't look awkwardly out of place then sometimes they do add a bit to the atmosphere. As far as the meshes are concerned, usually butterfly and fish meshes are as far as I'd go.