Washing hands before eating some kind of wet fruit has always been an extremely important ritual in Judaism. And not only in the religious sense.
In the Middle Ages, a terrible plague (also known as the Black Death) raged across Europe. In those times, a huge number of Jewish pogroms took place, due to the fact that the death rate among Jews was several times lower than among Christians. Historians explain this precisely by the highest level of hygiene among the Jewish people.
Urchatz also primarily concerns hygiene issues, so here the blessing is not recited, but the hands are simply washed in order to safely eat at the next step.