I agree that the game could need some different cultures (which will probably come sooner or later, considering the race choices and descriptions in the creation screen), but I am not sure how far those racial differences should go.
Different animal/building/weapon/armour/etc styles would be amazing, it would make exploration, travelling, and a cultural exchange much more enjoyable, especially in the context of the MMO and its much more diverse world with different climate zones.
It also could lead to a lively, diverse look in different regions of the world (e. g. [Auriun] embassy in [Auriun] style in an [Khalisian] city), trading (selling expensive [Jorgrithian] goods/furniture/weapons/armour in am [Auriun] city -> status symbol for locals to show off their wealth and global connections), advantages/disadvantages in battles (desert folk has no experience fighting in swamps, for example), et cetera.
I am not sure how far those specialisations or faction specific bonuses should go, though. That definitely needs some balancing, otherwise that could lead to some serious problems, but I could see how one civilisation has more advanced building capabilities, while another has more experience in creation armour and weapons, and so forth.