They're an Americanfishing/hunting/outdoors company-- so typically very generous sizing and not as "refined" as, for instance, Barbour. Good, hardwearing togs though.
Also, check out C.C. Filson. Their sizing is more versatile.
I agree entirely about the sack jackets. They were one (short-lived) skinhead item I could not really embrace. They made something of a comeback here in the 80s when there was a return, in London at least, to something approximating the look I was favouring around the summer of 1970 - Bleeding Madras sack jacket, BD, chinos/Sta Prest and penny loafers. Again it did not hang around long here although John Simons of course continue to promote that look.
There has been a debate on this thread and on the Mod to Suedehead one about whether J Simons or the current Milanese / Pitti look is the true successor to 'the Look' in the 21st Century. I am tending more and more towards elements of the latter (but still visit the great man whenever I am in that part of London).