I think it is a reasonable tradeoff, especially since `get(i)` is available to do what you want. An array index oob error is usually a logic issue, not some recoverable error, and in a lot of cases you're doing it where it is impossible to be wrong, so it is a lot of error-checking (and giving up things like x[0] += 1) to have the Index trait return an Option instead of a direct reference.