Pickling can have different levels.
Sushi was originally pickled and fermented. What separates the great from the average sushi chefs IMO is their skill with pickling to make very ordinary fish extraordinary.
Kohada, or gizzard shad, is tasteless and bony but is transformed when salted briefly and washed in vinegar.
Anybody with a sharp knife can make o-toro delicious because it's already innately delicious. The real masters know how to make the humble sardine transcend the toro.