In the Japanese original, Nadia's name was Marled... er... Marldia. She picks Marle in the original too. Though, Nadia was probably because of that five letter limit... Some people might want to name Marle her real name, but Marldia is too long... or... something...
And Crono not saying a word is for player immersion. It prevents playedrs from going "What? I would NEVER say something like that! This game sucks!" I think. Seems like silent protagonist is something used often in Square games.