The plus side of it being put off so long is that Paradox has finally gotten the hang of making good focus tree, so the Soviet Union having been put of so long means we'll be getting a much, much better focus tree than if we had gotten it, say, last year.
This is one of the only positives I can find in this whole situation, even though its painful to have the USSR tree like it is now.
I believe part of the reason for the USSR delay is that they wanted to couple it with a land combat revamp, which is probably the most important and most time consuming part of the game from a dev perspective, until then we get a pitiful placeholder tree for the most important nation in ww2 along with Germany.
As for Greece, it's likewise a development choice, I was actually happy Italy was not remade with La Resistance, because when we get Italy later on I bet we'll also get a Greek tree worked in conjunction, and I believe this will make both trees better because the devs can create interactions between the two.
This is likely why Mexico and Portugal were made when they were, it was for Mexico to couple with the US, and Portugal with Spain, if Paradox didn't paired those nations they would likely never make it into the game I believe so Paradox took that chance, and hey I really enjoyed the detail in Mexico's tree.
Some may disagree but I think Paradox decision here will lead to ultimately a more complete game (if you buy the dlcs that is...)
Having said all of that... I would still liked if the USSR took priority, so I guess I'm an hypocrite. . .