Currently, lvl 80 Ex trials, Savage and Ultimates do not have crit autos, but instead they have high rolls, this is mostly due to both the removal of Awareness as a skill, and more importantly you can't block a crit. So an increase in crit frequency would need to be more an increase of high rolls to allow PLD to mitigate the damage just as effectively as the other three, and that also goes for parry in the case of GNB and Camouflage's increased parry rate. Certain tankbusters have crit in the past such as critical hit in o3s (bit obvious) and Shinryu phase 3 tankbuster had a high crit rate (it hurt back in the day). Outside of those two examples, most busters usually are non crits.