It is not a limitation, as you said....It is because you overclock that you need the higher voltage. The mobile chip is new, build for mobile system, meaning that you cannot blame Asus or AMD for that. But if you want to push it way overspec, I think that ABIT NF7 can go higher than 2 volts with the newer BIOS.
-Always put the blame on you first, then on the hardware !!!