Back in medieval times armourer's made chain mail with tiny riveted links, no problem making the tiny rivet holes.
Watchmakers, jeweller's, the people who made the spinning and weaving machines of the industrial revolution, making an eyed hook would have caused them no problems at all, so why the straight shank?. Perhaps it was because the leader/tippet of the day was considerably thicker than more modern leader/tippet materials and was not so reliable when knotted, whereas a loop to loop connection could prove to be more reliable.
Also worth remembering that old habits die hard and as fishers we tend mostly to stick to what we know has worked before rather than risk the fish of a lifetime by trying something unproven.