eww... I don't know what you are into, but Echidna is not sexy, and shiva/sophia are designed to be beautiful (for lore reasons, not eye candy). Saint Shiva (while not resembling the primal), is known in legend for being Hraesvelgrs lover, and thus the worshipers would naturally create a very feminine figure (that I don't know if you have notice, is fully clothed) as per the legend. As for sophia, do I really need to explain why "the goddess" is beautiful?
Feminine beauty and allure is a character device that is difficult to attribute to a male (especially in a Japanese game, as the anime tropes are fairly concrete). Male nudity is usually attributed to power rather than allure, and creating allure from a male is very difficult and out of place when it comes to enemy design. The far easier thing to do is create female bosses that attribute power rather than allure, if "equality" (feminine allure is not any less than masculine power, so I don't know why equality comes into this, but anyway) is what you want to go for, give us Adel from FF8:
http://vignette3.wikia.nocookie.net/...20100528171023
