View Message

As a general rule I prefer the long form of a name than a nn as a given name. Longer, more formal names give a person more options as they age, which is one of the reasons I prefer them.
Some of the ones you've mentioned (Lucy or Lily)are full names that are also short forms of longer names, some like Ella or Jack have a long history as given names or don't automatically seem to stem from a more formal name. Short forms of names as full names come and go out of style, so I'm not surprised.