Brent Simmons & Manton Reece:
The JSON Feed format is a pragmatic syndication format, like RSS and Atom, but with one big difference: it’s JSON instead of XML.
For most developers, JSON is far easier to read and write than XML. Developers may groan at picking up an XML parser, but decoding JSON is often just a single line of code.
Our hope is that, because of the lightness of JSON and simplicity of the JSON Feed format, developers will be more attracted to developing for the open web.