The guild bank isn't a rubbish bin, and the guild store isn't Value Village. Damaged items don't belong in either of them.
That's not saying that we're not grateful to anyone who donates to the bank. But sticking broken equipment in the bank (if not accidental) can look like a lack of respect for your fellow guildies, firstly because that item then takes up a bank slot (and storage space is an eternal headache that the elders have to manage), when that slot could have been used for a repaired piece of equipment. Secondly, the player that withdraws the item might not realize it's broken, or be able to afford to repair it (which might be why they're using the bank in the first place, rather than the store, other crafters or NPC merchants).
As Elth suggested, guildchat is probably a better way to find a good home for unrepaired items if you don't want to repair them yourself, since at least it gives you a chance to link them/mention their condition.