Aside from the human connection mentioned in the post, by far the most compelling aspect to me is the "fixed" attribute. There's something so satisfying about isolating a problem, then fixing it.

Many charities feel like an investment. This feels like a transaction.

Edit: Here by transaction, I mean it's something that has a very high chance that it's working out. When I order a shirt online, there's a high probability it will get to me. When I fund a new t-shirt company on Kickstarter, it's less certain.