I'm sure this has probably been mentioned before, but I figured I would mention it anyway.  When selling things on the web (and outside the web), the cost of PCI compliance for software, websites, and small business owners can be prohibitive.  If they used bitcoin instead, they wouldn't have to go through a lengthy, costly (and ongoing costly) compliance with the PCI spec (and would still be inherently safer).

Don't get me wrong, I'm a big proponent of a lot of the PCI spec, but it can be a burden on small businesses.