Oh yeah you can only oc the CPU, Im sure they could find a way to push a button and oc the GPU.
The problem is not to overclock but to get rid of the heat... while CPUs don't get hot much more when only slightly overclocked, due the masses of transistors a GPU uses, heat goes up really fast... So you need to increase the airflow of the cooling solution, use more heatpipes, use more space generally speaking... more space increases the hight of the notebook which isn't what the people want. So be patient, MSI is trying hard to accomplish that, but they need first to develop a better cooling solution to do so.
best,
Eliot.