For a numerics-oriented language this is a good choice. It’s more consistent with mathematical conventions for matrices.

0-based indexes are commonplace in programming circles because of the C language, however 1-based indexes are the earlier standard set by Fortran.

EDIT: If Julia becomes popular outside data and numerics circles, it will have pulled off nothing short of a miracle in getting people to adopt 1-based indexes. This feud is older than vi vs. emacs. :-)