Sitting and learning to write as beautiful as possible may be great for most girls, but is an absolute horror for most boys.
I do not think this difference is inherent to gender. Some kids will enjoy what others despice.
If you see this tasks/gender alignment is because kids were exposed to different things, teached different things and consumed different media based on their gender
In other words: most differences are social constructed.
Kids should not be treated different because of their gender.
If you think that boys and girls are born with different tastes for activities then you may also think that australians are born with a genetic predominance to like vegemite, or that black people are born with a taste for rap music.
I agree that the individual comes first and that there is nothing wrong with a boy that likes caligraphic writing. Everyone should be able to do what they like without outside forces telling them how they have to be like.
But I think that there are inherent differences between the sexes (talking about averages not individuals!). And these are not just social constructs but rooted in our biology. From the perspective of evolution that makes a lot of sense. When evolution was able to construct mechanisms as complex as our eyes, it certainly figured out that in an asymmetric reproduction mechanism symmetric sexes is not the optimum.
But as I write above this is not really that meaningful. All individuals have the same rights, independant from their character or abilities. Before it was wrong to expect people to conform to their 'gender roles', now it is wrong to create a new unisex gender role for everyone. Becasue both is forcing people of their own path.