everyone owns that account, you know how to enter it yourself
If you send NXT there, than the first person to detect that, will send the NXT to his own account. In your case the NXT went to this account: http://87.230.14.1/nxt/nxt.cgi?action=3000&acc=15403621473314136443
Maybe he runs a program that checks the "easy" account numbers for incoming transfers.
I think this is so really stupid argument. If I want to donate it, I would rather donate it to someone I know, rather to random hacker running a bot by sending them to "null" account.
I doubt anyone sending nxt to "null" account are donating it. They are all new users making the same mistake. There is no point in arguing it's not a problem. Brain Wallet by itself is a for very advanced users who understand entropy.
It should be make much harder for users to just enter any random (or nothing) as pass phrase