If you had to worship one god of the Northern pantheon....

[Onyavar]

Odin [...] is [...] the leader of the traditional Norse pantheon.

Yet.

Wouldn't Freya love necessitate it ending in kids?

Oh, there are other advantages. It's good in the breeder's business: Rabbits, horses, cows... She promises a bountyful harvest, too, I guess. The less farmers have to rely on good soil, the more they need Freya.

People desperate for kids are probably but a niche in Freya's portfolio.