TVC would be somewhat important in doing advanced maneuvers without losing energy?
It is the whole plane making extreme vector changes creating massive drag that is the primary source of energy loss during 'advanced manoeuvres'. How that extreme vector change was induced, be it via TVC or control surfaces, matters little.
It is amusing watching western commentary on the TVC of the F22, and much of the kinds of 'special' manoeuvres the Raptor's TVC allows that would be impossible with just control surfaces are pretty much the same kind of extreme post-stall, minimum airspeed and retained energy manoeuvres that the, often same, western sources have been dismissing as tactically useless airshow stunts for years before when it was just the Russians doing it. Anyone remember the comments made about the 'cobra'?
Now, TVC does offer some real advantages over control surface, especially for the high altitude, high velocity minimal RCS air dominance fighters that true fifth gens are designed to be.
TVC would allow certain manoeuvres to be carried out without needing any control surface input. This would result in reduced drag and also help to avoid possible RCS 'spikes' when incoming radar waves bounce off a control surface at an undesired angle.
TVC control will also be much more effective than control surfaces if the plane is flying high with very thin air. Which is likely to be where stealthy supercruisers with AESA radars would prefer to be operating most of the time - the thin air will aid supercruise, while the high altitude will give the LPI AESA radar better range and also give any fired AAM much more energy and range, etc.
I havent heard a plausible enough explanation to list many more real advantages TVC have over fixed intakes.
The conns I am sure people are aware of well enough. So at the end of the day, it is up to the PLA to decide what is better. To do that they may well need to put TVC onto a test J20 to get clear results.