Consider n real numbers a_0, ..., a_{n-1}. That's not very elegant.
This discrepancy appears in physics too. It's common to use 1,2,3 for spatial indices, but when you reach enlightenment and think in terms of spacetime you add a zero index and not a four.
but good point, remembering academic linear algebra, seeing 0..n-1 in sigma/sums notations would be not convenient