The Greek gods were generally, in some way, portrayed as "amplified" versions of humans, and not strictly in a good way. More powerful, but also more jealous, petty, greedy. That extends to their appearance as well.

Consider how most of the men were sculpted as toned, muscular, all the markers of a man that has the leisure for exercise and sports rather than working the fields. However, Hephaistos was described as extremely ugly, which implied they didn't fear his retribution for presenting him like that.

Consider further that the majority of the goddesses' portrayals will have been made by men. It's hardly surprising that they'd project their preference for attractive women on them. Exaggerate that, and you end up with a bunch of really hot goddesses.

I don't think they were strictly concerned with flattering the gods. They were just men in a patriarchal society where treating women as objects of desire was normal.

Eh.

It might be less wise to sculpt something that was …unsubtle.