If they don't know your public key and your address never re-used, they can't crack it even when quantum computing is available for corporate.
If you are going to be bothered with keeping your password safe, you might as well keep your private key as well.
I assume this service is mostly for people who don't know a lot about Bitcoin, or just have so much money that they will keep a small portion of it in just about anything, to diversify their security solutions.
Right, and if you're paying to store your encrypted private key/s in Swiss vaults, it's pretty much a confession to the fact you have plenty of BTC to store. Rule number 1 in the Information Era: don't leak any information, however implicit it is!