Yes, because sea weed killers are an untradeable item which will by no means be available for a regular, non-maller player. I suggest you re-read my first post, I didn't say adding them to mall was the only way of bringing them to the game. I actually think making them a manufacturing item seems more appropriate considering its use, because it would be available to everyone (even though every item mall item is sold on the market currently, but oh well), and it wouldn't lead to oversupply.Seems like some people only think the way to be best on game is to spend money...well after so much complaining we can all see that if you cant beat them the solution is to get GM to add items to even boost the mallers further ahead of the game as it is already...
But anyway, first of all, you're saying that I want "to boost mallers" with this. I didn't say add equips or gems or leveling fruits in the mall, this is a miscelaneous item.
Secondly, I don't think you've ever used the item vs a few seavoys. It doesn't make you immune to algae nor that damage you take from curtain or ship attacks while you're algae'd by not one, but multiple ships. This item HELPS against SVs, it doesn't make you ignore them or their damage completely.
Thirdly, could you people for God's sake quit crying about how "adding something to mall would only benefit mallers". The item mall items here are sold REGULARLY in the market. Is it easier to get those items as a maller? Certainly. But isn't that how it's supposed to be?
so just enjoy the sea pk while it lasts 
HAHAHAHA