Like I said, everything hangs on Steam. If it fails you loose the lot.
I use a complex password and touch wood never had any trouble, however I have a friend who had is account hacked and while Valve sorted it out, half his games ended up VAC banned and Valve did nothing to correct this.
As you can imagine he is not the biggest fan of Steam.
When I consider the amount of money I have spent on Steam, coupled with Valves flaky support, it brings to light that apart for the convenience; Steam could be a lot more problematic than owning individual boxed copies of the games.
I guess these are the pitfalls of any digital distribution service. Just keep your passwords complex and stay vigilant.