Describe your suggestion in full detail below:

I think the Darkspear trolls should have their own culture diverged from the Gurubashi one, having been exiled from the mainland. I could be a fairly recent divergence happening around either when they were exiled or the time they joined the Horde, as it appears that its when most of their customs have changed.
They should probably have their own faith as well without the gurubashi's bloody feast tenet, since it was stated that they abandoned cannibalism once they joined the Horde, since it is forbidden although they still worship many of the Gurubashi Loa.

I also think that the Frostmane and Winterax tribes should be their own diverged cultures since they are a continent away from Drakkari, not to mention they left after the Sundering, which happened about 10 thousand years ago, more than enough time to diverge.
Not to mention the physiological differences, with both the Frostmane and Winterax being stated to look different from the average ice troll.

An argument could also be made for the Hakkari trolls having their own culture, since it is stated that they do not speak Zandali referring to it as "the old tongue".