Unfortunately the article doesn't do much to inform us of how this conclusion was achieved. As with most articles on education, I find myself asking more questions.
In my experience, it is certainly true that girls' work is generally neater than that of boys'. So what?
Has anyone been lauded for Presentation (arts aside)? Has anyone won a Nobel prize for Neatness? Does an employer hire the Best Behaved? Does Colouring Within the Lines lead to a happy, productive life? I don't know.
As a parent to children of both sexes, I'm neither alarmed nor inspired by this study and its conclusions, as presented in the article.