Prob'ly because of the Latin-based (esp. Fr.) names ending in
El... Like
Belle,
Isabelle,
Raquel,
Rochelle,
Laurelle, etc.
However, Hebr. names for boys frequently contain "
El" in reference to G-d.
RaphaelGabrielEzekielElijahElkanah
Once you get the concept of it,
Ariel can grow on you as less fem... esp. if you have Jewish friends and aquaintances.