I agree, just wishful thinking since it'd be much easier to bring new characters due to AT's. We'll see.
From what I can see, depending on what you call "important", there are 2 that we have been talking about. Note that I don't think obscurity plays a role here because even more obscure characters from these series are in yet these aren't:
- Porky: The mother series mos prominent villain. Other super obscure characters are there, but they forgot to add Porky? Odd.
- Sylux: Every other hunter is there, except Sylux.
Thats kind of it at the moment. It is kind of funny that these 3 characters specifically missing out of a 1000 plus spirits, when Porky is the most notable mother villain, Rhythm Girl is the face of RH, and Sylux being the leader of the hunters, yet all 3 series have more obscure spirits.
It could mean something, it probably means nothing, but its something to keep note of since Nintendo is making DLC and we honestly don't know if 3rd parties are going to be a huge push this time (we only have rumors, and allegedly Minecraft/Microsoft isn't even panning out).