Inerting the wine during pressing is not essential but can improve quality considerably.
Studies have shown a decrease in vegetal aromatic compounds and MND when the pressing is carried out under inert conditions. It is potentially possible to produce fruitier press wines. This is particularly true for vegetal aromas.
Considering the amount of lees present in the wine at this stage, which are capable of capturing some of the oxygen, it is questionable if the difference has real a impact on premature oxidation compounds.