The Harrier has been around a while so I'm sure what Mogwi said is correct. But lets examine a hypothetical future aircraft.
The Harrier needs all of its thrust to sustain a high g turn. If you use some of this thrust to temporarily increase pitch rate then speed falls off. A future aircraft might be able to sustain limiting g at less than full power. If this is the case and it is capable of thrust vectoring, then the forward component of thrust may still be able to sustain limiting g whilst leaving some thrust spare to generate nose angle. Obviously its a little more complicated than that in that alpha is also likely to increase which will have a significant effect on drag and there may no longer be 'spare' power available to generate nose angle.