The idea behind the criterium bend is that they had minimal extension and drop. It put you in a good position to sprint out of the saddle which is what you do out of every turn in a criterium race.

Also the bend makes it so your wrists and forearms dont interfere with the bars. All my racing was done on Giro d Italia and Campione de Mondo bars. All summer long I had painfull bruising on my forearms from pulling on the bars out of the saddle. But back then you took what you could get and no one told me about criterium bars.