They want to build him for this reason: Huntsman is not a religious candidate. His views on climate change and evolution and gay rights make him someone that the media wants to root for.
Gary Johnson:
Believes in evolution
Believes in climate change
Is gay-friendly
Was a 2-term governor
Why won't the media cover him (he's living off scraps right now while Huntsman is wasting his large amount of coverage)?
Johnson also advocates for legalizing marijuana.
I think the mainstream media writes him off as a result.
But the whole idea is Huntsman is controversial.
That Atlantic article explains it well - Huntsman is "controversial" because he challenges GOP base. If you challenge bipartisan assumptions, like drug prohibition, you're not "controversial", you're a non-entity. Also, Johnson is not a kind of guy media connects with, he seems they probably see him as some backwater weirdo while Huntsman is the guy they would love to be friends with.
Also, don't forget the hair. Media will whore themselves for any candidate with soap opera star hair, just like they did for that pathetic empty suit also known as John Edwards.