lack in Ease of use is one of the things preventing people from using BTC, now with a credit card you simply do not need to do anything but hold the card and pass it in a device, BTC require a little more, also it's value is not stable to USD but floating which is not convenient for your typical money transmission method.
Ya right and people are used to credit cards as they are using it since long time, and for them using bitcoins is something very new, and as they are not aware about the bitcoins they will not use it, but people are guided in a proper manner then they would surely start using bitcoins, lack of knowledge is responsible for it.