There's nothing hard sounding about Agatha....?
And again, it's only fashion that dictates how names sound to the current generation.
At the moment girls' names are are very frilly and feminine with 'y/ie', 'elle/ella' and 'a' endings - Millie, Lilie, Evie, Ruby, Daisy, Sophie, Annabel/lle, Isabelle/a, Amelia, Freya, Olivia, Sophia, etc, etc, ad nauseum.
But a generation or two ago, the taste was definitely for less frilly names with consonant endings, e.g. Helen, Joanne, Karen, Nicole, Janet, Jane, Ann/e, Catherine, Susan, Margaret, etc, etc.
People are already beginning to get sick of the overtly feminine names. The switch back to less frilly names will happen, just as the cycle of fashion always continues to turn.
And then the names won't sound 'hard', they'll sound because that'll be the fashion of the time.