Well, gee, Bender, it's because a longbow should be long. And because most of we veterans who are fair hands do our best work with longish ones.
And because Mr. Hill himself suggested that the last digit of the bow length should match the last digit of draw length. So he used 68" bows to match his 28" draw. And I use 70" bows to match my 30" draw length.
Isn't your current bow, a Lee or a Fox as I recall, longer than the little stick you started with? Not that a shorter archer should not use a shorter bow.
I am also fond of the notion that if an archer places his strung longbow on the toe of his boot and his hand on the upper tip, as he poses for the camera, his hand should just clear his eyebrow and not block his manly face. I deduced this rule from many old photos of the greats of our sport. I myself prefer to pose that way. - lbg