I would like to say if you consider yourself a soft-polytheist, this is not an attack, just a few personal opinionated ramblings on why I'm not too fond of it..
Soft Polytheism is where many (or all) variations of Gods and Goddesses are merged into one, or as Dualtheistic One God/One Goddess.
Why I don't 'agree' with this concept -
Well for starters.. why would anyone want to give a deity a mental disorder? I for one wouldn't want to worship a god with split personalities because that might confuse them .. and open the door to schitzophrenia or something worse. Take Eris for example, please! ... (lol 2 points if you get that old joke before you read this text in parenthesis) Would you really WANT the Goddess of Chaos, Disorder, and Confusion™ to be any more chaotic, disordered, and confused? Seriously! I also don't think she'd want to share with any of the "original snub" Goddesses either (Discordians will get that, if you don't.. it's ok).
Secondly, and seriously, I find it hard to believe that many other deities from other pantheons would like to share an apartment.. let alone share deity-hood. It sounds more like a cosmic reality show, rather than something to worship. "Next week on the program: Freyja uses the Morrigan's bathroom, which erupts into a cat-fight!" C'mon.. we really don't need situations to arise like that!
Maybe it's more convenient to those who do use this way of thinking. Which is also a bit awful IMO because you are taking away from the rich myths surrounding individual deities. If you lump them together in one category, you are in a sense creating a new deity, which is not really an improvement. You can't mix a rock and a tree together, just because they are both 'part of nature.' That would be silly. They are seperate beings for a reason, and have their own mythological histories. Now granted, in the P.I.E. traditions, there are deities with similar aspects (Odin/Zeus as all-fathers, Danu/Frigga as all-mothers, Freyja/Aphrodite/Venus as love and fertility Goddesses etc.. ) but they are still separate, and have some different traits from their alleged counterparts of other pantheons. However, the concept is that ALL of them are one God or Goddess or both. It seems to me like pure laziness. "I can't be bothered to remember all their names, so I will say they are all one! This solves everything!" WRONG. If a friend asks you to pick up a cake (or pie since we are talking about proto-indo-european religion) and you end up getting cookies, because "Well they are ALL desserts!" your friend might have to slap you. Well I would hope they would anyway.
Ah. Well this is food for thought.. speaking of food.. anyone got any pie?