If the main plot was “Buddy and Jovie fall in love,” then the scant attention on Jovie’s origins would be entirely remiss. But Jovie’s backstory is minimized because their romance is merely a subplot. The main plot concerns Buddy finding his bio dad and attempting to build that relationship. It’s the story’s thru-line: it’s why Buddy leaves the North Pole and his overarching, hard-to-reach goal.
The relationship with Jovie is incidental (and cute). It gives Buddy a “win” while his main goal (Dad’s love) is eluding him. The romantic subplot prevents this comedy from becoming too much of a downer, but equal focus on Jovie would throw this parent-child reunion tale off balance.
A whole new screenplay with Jovie as the main character who — against her better judgment — takes up with a man-child raised by Santa’s elves, could be quite entertaining and maybe even explore the feminist question of why some heterosexual women settle for so little.