you more or less summed it up here ,there is no one right way to sharpen a chain ,off the roll new is a compromise that cuts "ok" but holds a sharp edge longer ,the sharper you make it also means it may dull faster due to the thinner cutting edge ,another compromise ,i would rather have a smile on my face every cut i make though and sacrifice some longevity ,and have to swap chains more often then cut with a mediocre tool
also some think the square chain i run takes longer to file ,i do not think it takes any longer if much anyways ,3-4 short swipes and a cutter can be touched up real nice here is a bad demo vid of sharpening square i did a while back ,it gives the basic idea of filing square ,but i was doing it one handed to video it ,i normally hold my left hand on the chain to stop file chatter ,this file was not the sharpest either