It also makes modulo math easier. Starting at the first element in an array and jumping to every 8th element thereafter gives you indices of 1, 9, 17, 25, etc for 1-indexed arrays. It's not immediately, intuitively, obviously clear that the index is 8n+1. However, 0-index arrays would be 0, 8, 16, 24, which is very clearly 8n.

There is no argument for 1-indexed arrays other than, "so-and-so can't be arsed to learn 0-indexed."