I'm more confused about your perception of Evelyn. To me it fits right in with all the soft satiny names like Ava and... Avalynn... it's just the name that people who secretly want to use Avaleigh or whatever use if they want to pretend they're tasteful, it's totally fashionable phonetically. However, I do remember feeling this way about Isabella, in, like, 2005.
Lillian is a little more dowdy and mealy than Evelyn. It doesn't seem particularly surprising to me... I just think of parents who want something more formal for Lily.