I was queuing for a dungeon and become bored so I was browsing UESP and noticed something about the guild traders. With 204 of them you'd expect some good diversity among them, but the VAST majority of them seem to be among the following:

Female Altmer
Female Argonian
Female Bosmer
Female Redguard
Male Dunmer
Male Khajiit
Male Orc

In fact, before Orsinium was released all of the guild traders fell into that group.

We got female Orc and female Breton with Orsinium.
Male Redguard, female Imperial, and male Breton with Vvardenfell.
Female Dunmer, Male Nord, and....a factotum....with Clockwork City.
Male Altmer and male Argonian with Summerset.

But even with these gradual new additions, the previous group of gender/races heavily outweigh the rest. And we've still yet to see a male Bosmer, male Imperial, female Khajiit, or female Nord selling their guild wares.

Anyway, I think I read something about not wanting too many voice actors or something along those lines....but maybe Murkmire will add these elusive traders to Tamriel.