Now, one of the things about BR that always endeared me was the fact that humans felt unique a Khansi human was diffrent from the Anuerian was diffrent from the Rjuven was diffrent from the Brecht, was diffrent from the Vos. Part of this was the +1 -1 that humans got.

3E Made humans even more blended, and to keep the balance right internally, BRCS had to make some comprimises. Overall for 3.X BRCS did a good job at making humans subtypes feel unique.

4E Balance changed, Humans in general are still generalists, but instead of the standard +4 (+2 to two diffrent stats) that other races have, Humans get a +2 to a floater.

To bring back the flavor of 2E I think to start with, the easiest change is just to give each race at of +2's like a normal race. Humans would still have some of the versatility of their stock standard 4E counterparts (Namely, the extra At Will and extra Feat and Extra Skill), but it brings back the feel that 2E's races had.

My Suggestions
Anurieans: +2 Wis +2 Cha (Charisma drives the Warlord, which I see a lot Anurieans being.)
Issue with this: Wisdom and Charisma are both Will Save drivers, its possible to give a +2 Int, but I am unsure if we want that. Maybe +2 Str or +2 Con.

Brecht: +2 Dex +2 Cha (Charisma is the sneak-thief rogue favored attribute as well, which I think a Guilder/Merchant style would be more likely to wnat)
Issues: +2 Cha seems to be popular with races, but Paladins, Clerics, Warlords, and Warlocks all have lots of abilities that key to it, and Rogues have a fair number sooo charisma seems to be more popular overall.

Khansi: +2Int +2Wis (Status/control wizard)
Issues: This hasn't been done in the PHB or MM stated races, has potential be abused with Orb Mastery.

Rjuven: +2Dex +2Con - this one is the one I am most happy with race wise, it will lead itself to rangers which I see as prevaliant in Rjuven.

Vos: +2Str +2Con - This just plain makes sense, though I think the Vos will benfit even more from this once Primal sources comes out.

Issues: Strength and Consitution both help Fortitude Saves, I think over all though this won't matter as vos are going to be heavy into the defender classes. Maybe replace Con with Str for a strong two-weapon ranger build, but it feels weird to put ranger with Vos. Evne though 'ranger' doesn't mean 'good guy' automatically anymore.