Some fans definitely agree that their romance isn't the series's highlight, but I always thought it made sense. Ginny had a crush on Harry for years, and marrying her connects him with the Weasleys, the family he's been closest to his entire life. It even connects him to Hermione; Harry's wife's brother is Hermione's husband, so they're now siblings-in-law, allowing everyone to remain together even after Hogwarts.
Ginny is also a fan of Quidditch and shares Harry's spunk, Hogwarts House, and slightly-rebellious nature. The films don't have as much time to explore their connection, so I can understand your thoughts if you're referring to them.