Yeah, people mostly jump on Humble Bundles because they get a ton of great games for insanely cheap prices. But I like to think that the fact the bundles donate money to charity also plays a part in their success, giving gamers the chance to see their money go somewhere useful, instead of simply drifting down the river as returns for shareholders.
I can understand if the mere fact the bundles donate a percentage of profits to charity is enough for most folks. They can assume the money is being well spent, feel better about themselves and get on with their affairs. But if you've ever wanted to see where part of those proceeds actually end up, and get an idea of the difference the money is making to people's lives, take a look at this.
The Humble Bundle Mojam, offered last year, "saw 81,457 Humble Bundle customers contribute a total of $121,780". That money was handed over to Water Aid in Ethiopia, who used it to build six "water points" in the country (three wells and three tap stands). It might not sound like much, but those points now provide 3000 people with clean drinking water every day.
Your money didn't end up in some vast pipeline labelled "charity", lost amongst administrative costs and political back-handers. It went straight to where it was needed, and it made a difference.
So yeah, enjoy the cheap video games. But know that even when you're done with them, the awesome thing about the Humble Bundles is that they just keep on giving, long after the credits/Game Over screens have rolled.