I remember Doomdark's comment on this, and he himself admitted it was an arbitrary split made for apparent balance reasons, though personally I am unaware as to what they were. Why shouldn't Rus be a huge kingdom? It certainly was historically. I also re-add Khazaria (remember that?) as an empire rather than a kingdom, encompassing all those brownish Steppe kingdoms. Much prefer that setup.I might just do that myself, though I understand why they did it.
(Oh yeah, and the Russian Empire is obviously removed in such a setup...)