I hope you are not thinking that in VM we only calculate from left to right, because that is not so. Both are useful and the Vedic mathematician chooses the best method at any time: right to left or left to right.
Certainly right to left is better sometimes, and educationally it makes sense to learn right to left first of all because we start with learning about units before tens and so on.
We do focus more on the left to right direction on this course, but that is because people are very familiar with right to left methods already. And as you will see there are many advantages of working that way.