I'm with you here, well tied bowlines shouldn't come loose often. I've
had it happen a few times on a lazy sheet but I've had more sheets
break than bowlines wiggle loose. I really don't like putting hardware
onto the clews of non-boomed jibs. Jibs will flog and eventually
somebody will get hit by them. I nearly lost my brother when he was
hit by a jib that had tied sheets on it. Knocked him out cold and I'm
sure he'd be dead if we'd had hardware on the clew.

-- Tom