Then why bother unless you have a specific reason. (i.e. long term conditioning, lagering, adding fruit, you want to "free up" your primary)
Because they result in two different tasting beers. That is a pretty big reason to chose one method over the other. This is what the article in BYO showed. Primary only beers tasted different from those that utilized a secondary. These are not huge difference by any means, yet the tasters had clear preferences and were evenly split as to which method they preferred.
My "argument" is to try them both and see which you prefer. Either way is a perfectly acceptable way to ferment your beer. You do not need to leave your beer in primary for an extended time to make good beer. However if you like the flavors you get doing it that way, then by all means do it that way.