Online wallets like block chain or coinbase are safe only but still hackers are scamming in online wallets. Better you would go ahead with offline wallets, paper or cold storage to keep it safe. That is the thing i know online wallets can be unsafe but i have had a small amount in blockchain.info since i started here. I say small but we are talking a couple of btc. If you have just a small amount then as you say they are safe enough. When you get to 5 and above btc that is when send to cold storage just to be sure. If you have good security and dont surf and download from dodgy sites all will be ok. I only leave on exchanges what i could lose, they could run at anytime..