I would imagine there is an objective reason for each argument: left-aligned for readability, centered for balance. But I think that centered makes more sense. You have a cavern of white space when you left-align the table, and if you study layouts you'll find that while white space is indeed a great thing, it's not great when it throws the whole page out of balance.

You can align the text left on that invisible line, right on that invisible line or have the text centered on that invisible line. Justification is a lateral horizontal measurement based on one of two invisible vertical lines - left and right for justified text or left only for unjustified text.