As someone who has advanced pretty far in stories without ever having enough echoes to get the larger ship, I am constantly having to dump tons of valuable material into the sea when a storyline gives me an unexpected bounty of something or other. Also, last time I went by the Salt lions to pick up a load, I accidentally clicked on that option a second time, and it gave me another load even though I had only one free space in my cargo.
I don’t remember this happening that often before, but maybe it’s only because I was rarely getting pushed 20+ things at a time. Still, it’d be nice to see what items an action will give you before clicking the action, or at least get a "this will give you more items than you have space for. Proceed?" pop up.
I forgot to sell my stygian ivory at polythreme before picking up the clay men. I dumped them, sold the ivory, and picked up a fresh batch of six. Felt terrible, but a captain must zail on!
I seem to recall that, a while ago, it was implemented that you wouldn’t have to dump anything until you actually tried to leave port - giving you a chance to sell or otherwise make use of excess cargo. But, if that was in place, it seems to have changed since (hopefully temporarily!).
At the moment you have to dump everything the second you go over the limit, which is understandable, although it would be a good option to have to be able to wait till you’ve left port before you have to drop things.