1) It maintains parallelness betwixt zucna and dutso.
2) I want to avoid conventionalizing Lojban. Choosing the right-hand rule
to be the basic rule for all Lojban definitions has far-reaching
consequences in all areas of mathematics, even basic ones like trigonometry
(the direction of positive angles), very basic introductory algebra (x and
y axes), and complex numbers (if using the left-hand rule, angles are
measured clockwise; it would be most natural, in the context of other
conventions, to make upward be the positive real direction and rightward
the positive imaginary direction).