Unfallan conflicting design

After considering this a bit more and taking into account the fact that you are able to eventually "use" influence to take over systems I would say the problem really lies in how late in the game they can really take advantage of vines and influence. They are very late game heavy and very weak early on. Perhaps the change to Pirates contributed to that, making the Unfallen really become not only very weak(by itself not too bad for a single player experience) but also not fun as they are so RNG reliant.

I guess there is a connection between a race being fun and also powerful and once a race becomes too weak you really dont ever feel like you are able to do sometihng interesting with it when you play, no matter how hard you try to optimize.