maybe I'm being dim but what possible aesthetic benefit does it offer? The only benefit that springs to my mind from a language design perspective is that it is most likely familiar to the user of the language from languages they have used before.

Both Smalltalk and APL use 1 based indices so I just find any claim of obvious aesthetic superiority on this issue a little hard to accept without some back up.

If speaking aesthetics the fact that the number of items in your array is equal to the position of the last index item in the array would seem aesthetically superior.