Although from the start, it's completely asinine to make such a stark comparison between essential compounds like water and "EFAs", or even oxygen for that matter as they're all just pieces of chemical equations...
There's an awesome synopsis in the latest Psychology Today about your topic:
How men's minds reveal the wisdom of women's bodies
Long story short version of that piece is
-Women predominantly house their DHA stores in their hips
-These stores are broken down in the later stages of pregnancy during the more important stages of the fetus's brain development
-Women with higher DHA stores (and a better waist-to-hip ratio) produce children that are more intelligent, more successful, and reach sexual maturity faster
-Men rate female body attractiveness largely related to their waist-to-hip ratio (women with a better ratio even cause special neurological responses in men hence why porn stars are shaped differently than runway models) most likely for the reasons listed above as it would ensure more successful offspring