Scott, you're right. For the sake of an extra 1 to 2 hours of initial development time the individual json values should be sent to SQL as separate columns or the json broken apart by a stored proc and then inserted into columns. Either way the native power and full range of SQL functionality can then be applied to the business data.
I'm not knocking the json/sql library, I think it's very cleverly designed by Joshua and I'm sure it will be warmly greeted by many developers or DBAs who already have a json column which is, until now, very awkward to query.
Heck, I just remembered we've got a column of json! It's only intended to be squirted into a web page for browsers to read, but with this new library I could query that data if there was a future requirement to.