Poor Octopus-san. :(
I wish people didn't feel the need to salt and boil their seafood alive, even if it does make it more convenient.
It's not really about the convenience when it comes to seafood, it's more about freshness, especially for seafood the fresher the better. Chicken, pork or beef can be stored fresh frozen or near freezing temperatures for some time. However, seafood cannot retain their freshness nearly enough once they are dead, since seafood tends to go bad very quickly. Even if they are frozen, seafood loses a large portion of their flavor once they are frozen. This is one of the prime reason you really only see really good seafood restaurants near the source of their catch or they own a temporary tank to keep the seafood alive but increases the cost due to the extra maintenance.