I could create a program to randomly shuffle words in 24 word strings (the most words MultiBit allows to create a private keys with), to create private keys and check them for a BTC balance on the block chain. If the keys' address had BTC allocated to it, I could simply withdraw it to my own, untraceable wallet.
I suggest you try it. Electrum version 1 wallets uses 12 words, half of Multibit. Create the script and run it for a month. Electrum uses a list of 1626 words, total permutations is 3.4 x 10^38. Have fun with it! You might just be lucky and hit a wallet with balance on the first attempt.
I think there are people who tried it before and some still hacking. I haven't heard of any Electrum users reporting that their coins are mysteriously gone.