I think its not about blockchain.info and bitcoin-QT. Its about web wallet and local ones. Ideally web wallets are not recommended. But with the increasing popularity and wider usage of Bitoin, more virus and malware will be created to affect machines and take away coins from local wallets. So for an average person, it is probably safer to use a web wallet, keeping in mind that the wallet service provider may rob the coins too.
That may be true, but there's still another factor to consider.
If you have $15,000 in cash, your only options aren't to either keep it in your pocket or let someone store it in a bank in Romania. You can also take $12,000 of it and store it in your underground safe at home.
With bitcoin, the underground home safe is called an offline wallet. Done properly, it CANNOT be hacked; the ultimate in digital safety. Even if done in a less-than-perfect manner, your chances of getting hacked or defrauded are still greatly reduced. Add that you can create backup copies and even split the keys if you want (like with Mycelium's encrypted backup that also has a passcode,) it's a no-brainer.
Again, if someone only has $200 or so in Bitcoin, I understand them not wanting to go through the hassle. But for large amounts, not taking the time to secure your funds with an offline wallet is just lazy, and won't end well.
New users need to understand this!
