Not unreasonable. While the alien races are, well, alien and there's no reason to expect that they would conform to
H. sapiens morphology, the "Anomaly" type available in the Appearance Modifier is clearly intended to be humanoid. Since there is sexual dimorphism in the general structure of the adult human form, it's reasonable to expect that the suited Anomaly-style avatars would reflect that. There is one body form which kinda sorta maybe looks female but HG could do better.
While I would hope that HG doesn't go overboard, the covers of classic SciFi novels on which NMS is ostensibly based often depicted rather, er, obvious females, so there's that argument as well. ;-)