I believe so, yes, because they never explicitly said Void Elves would never be able to have access to natural skin/hair colors.
Indeed they do. And I feel that they love to retcon. Likely because they can’t keep track of all the lore, and it’s normal, it’s been what, +15 years already. But I still remember when Suramar was supposed to be destroyed and under water. 
While I understand your point, I don’t agree with it - I really need an explanation if not for all, at least for most of the customizations. And I do hope Blizzard shows us in game where these customizations are coming from. I don’t need cinematics or quests or whatever. A simple short NPC dialogue or a scene where we see Void Elves channeling Void into High/Blood Elves is enough for me (or your wonderful Void storm idea, but I guess that would require more work form them xD).
Indeed, and like I said, I don’t think it’s an issue that Worgen players have access to a tail. I’m indifferent, and I’m always in favor of diversity and more options. But I do like to respect a certain level of consistency when it comes to lore. Many people appreciate lore (I mean lower case lore, but we also love upper case Lore <3), and I feel that retconning “worgen do not have tails” would feel bad for those people. It would imply a loss of trust - this new content that is being released, should I get emotionally involved or attached to it, considering that it might be retconned in a few years? That’s my point, there - regardless of whether Worgen players ever have access to tails or not.
Oh no, I won’t ever deny players something they want, you know this very well. I would suggest them though to offer a lore-compliant explanation to why certain Worgen would suddenly have tails. To help them with their cause, mainly.
I can think of a second generation of Worgen, with a different type of curse, where they develop a tail, for instance. That would also be cool because Worgen would have to deal with two types of curses now, and imagine the new lore potential of it. 