I would love to see more of it Coin, and I enjoy incorporating spirits into play and plot.
But. I have seen this be a pretty huge barrier to people. It makes me sad regarding Werewolf because it's so vital to the theme. But for whatever reason it can be a barrier. And not every st will feel comfortable asking a staffer for a walk through when they can just do a kill this thing or find this thing.
That's why I'm not sure banning a class of PC gets you more activities in other areas. It may give you more pcs of the desired type (who then hang out and do social) but it doesn't usually solve the problem of why there is an imbalance in the first place.
I love the ephemeral stuff, personally. And I like incorporating it. WW is fun because it's so essential.