I would too, even without etchings.

The etchings nonsense was discussed here when it first appeared. I passed the link to that discussion to Plarium, but I don't expect anything to change.

Sadly, it is not possible to remove the cannon, so just keep it at level 1. If you click "Upgrade" by accident, it still won't use etchings, unless you do it 6 times.

should of made it once upgraded it could be brought back up for free like levels to 6 

At the beginning of the Pirate Bay server, I saw purpose in the resource-boosting cannon. With the server so far developed and having so many DEAD HAVENS to raid from players getting fed up with the game and quitting, I see no reason to have the cannon anymore, let alone the added feature of being able to waste etchings on it. 

To answer your question, yes, I have made the mistake of using my etchings on the cannon whilst logging in and being in a rush. It's got me twice now. I said so many bad words, probably even a few some of you may have never heard too. lol

So, the Cannon is useful. It's educational, as you learn/invent new bad words. 😁