This is a mistake perpetuated from old array languages.

Evaluation from left to right is more natural to people using latin alphabet.

It's totally arbitrary anyways. I suspect the only reason why there is right to left evaluation in APL family is to support assignment like this:

  x: 1 + 2 + 3

which would have to be the following in left to right

  1 + 2 + 3 :x

I think most people would agree that 'a:f g h x' is easier to read than 'x h g f:a'. This may be an artifact from familiarity from math or something else, but I think the point still stands. I've personally never found RPN languages easy to read.