If balance were a high priority, if evoking classic feel were the higher priority, rolling like you did back in the day would be front and center. And it is.That's the interesting thing: the ranked-average /is/ really close to the array (heck, it might be where they got the array, it's that close, to w/in rounding differences).
This is just a personal impression from running too many 1st-level intro games, but random generation can give you one or two particularly good PCs in a party, who can then help 'carry' the party. Array, you're all 'just OK,' and no one's carrying anyone....