They will probably put it in the Expansion. Other wise the reason is probably because people are complaining about how bad it is. Remember, Starcraft 2 isn't finished yet. :)
New awnser:
Old awnser failed. there is no expansion, and beta is out, so no new unit will come out. it is because it was over powerd and got replaced
zerg rush
Zerg is an alien race in Starcraft.
To have access to the Zerg units, it is really important that you pick "Zerg" as your race.
Terran,Protoss, and Zerg
The Zerg .
If you mean the three races, they are Terran, Zerg, and Protoss.
The game will be split into three separate products, based around the terran, zerg and protoss campaigns respectively. The first is called StarCraft II: Wings of Liberty, the second will be called StarCraft II: Heart of the Swarm and the third will be called StarCraft II: Legacy of the Void. So if by Starcraft 2 you mean Starcraft 2: Wings of Liberty then yes only terran but there will be three game products for the zerg and protoss campaigns.
Welll I beat the story mode and I only got to be Terran and Protoss.... i only wanted to play Zerg too....
Terran, Protoss, Zerg
If you are referring to the game Starcraft, then the zerg queen is Sarah Kerigan who was transformed by the zerg and has become one of them.she was imprissoned by them and was formed into a zerg queen. she used to be raynors friend. but now she's not
According to legend, the great Xel Naga created the Zerg and the Protoss, and it is fated that the Zerg will eventually defeat the protoss while being led by the Hybrids.
No because you're only playing as kerrigan working w/ zerg.