As a fallout babille "reader"as you say you are you shuld know that Fallout mmo will got the place betwin f1 and f2 so deathclaws can be in with no lore problem.
You're wrong. Well, you might turn out to have guessed it right, but for now, the time period the game will take place in has not been yet announced. And as I said, most of the makers of Fallout aren't very fond of the talking deathclaws either, so it is rather doubtful that they'll be back. Furthermore, thousands of talking deathclaws running around towns and freely interacting with people would not fit the setting.
As for Cyborgs /Androids alot people agree with having those races.A mmo with only 3-4 races will not apeal to alot of gamers and will make it very simplistic in this matter.
I don't see how dozens of races are a must in a MMO. 3-4 races is pretty much standard actually, even for high profile games like Age of Conan. Cybernetics is extremely rare in the Fallout setting, and androids even more so, so again, having thousands of players with these "races" would be silly within the logics of the setting.
In fallout tactics we got all kind of hybrid classes like robots etc.. and they were very cool and not with "balance "problems as you state.
Fallout Tactics was not a MMO, but a tactical squad based game, where the individual characters didn't have to be balanced, as long as the squads were (and even then the point system was very unbalanced). 
Stick with the thread "For V13, what race would you be and why?" and not what races you dont wana see becouse no one realy wana know what races people dont want to have in v13.
Discussion of what races are plausible in the Fallout setting seems very much on topic to me.			The Vault - Fallout Wiki * Fallout Online * Fallout IRC Channel *  Fallout: New Vegas