This idea has been discussed in the past, extensively but without conclusion. I would suggest that you may be interested in the following preceding threads. Many very important points have already been made in those discussions, and I hope you’ll find it helpful in shaping your idea:
It is important to note that the existing unlabeled subscript is safe (because crashing is safe, since it prevents execution from continuing in an unexpected state) and it is checked (since it crashes precisely because it checks whether the index is out of bounds).