I know this is a very simple question, but why do we make a boracha on netilas yadayim and more specifically, why do we say “v’tzvivanu” on this d’rabonon?
We say v’tzivanu on many mitzvos m’d’rabbanan. Why are you asking on netilas yadayim and not krias hamegilla or hallel? Or achilas maror for that matter?
It could be for maror that the lashon “asher kidishanu ..al achilas maror” is thanking hashem for the original mitzvah of maror that was the makor for the takanah which we have today.
This could also be a reason for the lashon “al achilas” and not “lechol maror” since we are not actually now doing the mitzva.
So why do we say “al achilas matzah/maror?” According to those that a continued mitzvah gets an ‘al’ we can answer that korech/afikoman are continuations of these mitzvos. (retraction from previous post)