Why is Canning a Relatively New Phenomenon in Craft Brewing?

Canning is a relatively new phenomenon in the craft beer industry.  Why did it take so long?  If you said "demand and supply", go get yourself a bottle - or can - of your favorite brew.  If this simple explanation is, well, too simple, then check out this article in Examiner.com.  It offers a deeper explanation about the aspects of demand and the aspects of supply that drove small brewers to package their fare in bottles until recently.  I linked to the article in the update to an earlier post on premium wine vs. premium beer, but later thought it deserved a link in its own post.