I remember there was this program I saw ages ago which is about left hander vs right hander brain activities etc. I think it was a study about creativity and logic side of the brain.
They conducted the experiment on a pair of identical twins, and they had to explain the reasoning behind it, and how they raised one as a left hander and the other as a right.
Here they explained the concept behind left and right handers:
There's no such thing as "left hander gene", contrarily there exists a "right hander gene" which is dominant. The gene basically forces a right hand preference in the person.
The twins were born without this gene, so they're free to grow up as left or right handers, and it's the external influence that drove them each way.
I can see advantages in the right hand gene due to the examples named - if everyone's right handed then it certainly makes life a lot easier where instruments are concern. On the other hand I certainly would think it's more benefitial to eliminate the right hand gene so that we can "train" ourselves to use certain instrucments with right hand and certain with left.
I was a left hander as a toddler but got the right hand beaten into me for writing. I still struggle to do certain things right handed though - the stuff that my dad never took notice of.
I still write with my right hand because of the way letters are shaped, you'd be pushing against the paper to write left handed. However I can draw large stuff left handed, precision drawing still in the right.
I can't cut meat with my right hand so I hold my knife and forks opposite. I can't peel oranges with my right either, and I can only pour liquid out of a container properly with my left handed, as well as holding mugs with my left by preference.
However I can do better kicks with my right in martial arts, though my left caft is massive cuz I do all the balancing on it while kicking.