Here's the actual secret: variance in gaming is fun.

Critical hits are pervasive in gaming (and have been for decades) because that dopamine hit from a gigantic direct hit crit on your biggest ability is an experience that hits the dopamine. In FF14's case, it also opens some design space for moves that auto crit/auto DH instead of the normal chance-based proc.

Also, that one time that you didn't crit isn't why you hit enrage