Armed robberies are more common, since arms are more common. from 2003 to 2007, there were roughly 3.7 million robberies per year in the US. Those are older stats, and i'd imagine the numbers are much higher these days. Access to guns and the gap between the haves and have nots is only growing.
Armed robberies are more frequent now than in the past, but a simple explanation is the reason: there are more banks and more guns than ever before. Couple that with the ability to receive news on a nearly instant basis and you have a recipe for what appears to be more armed robberies.
I think that they are. I cannot say with any valid proof, but I have to think that people are becoming more and more dependant upon money and will go to great lengths to get it. Morals seem to be going by the wayside, with fewer and fewer people having any regard for anyone else. People would just like to get money the easy way.
If it seems like there is a sudden crime surge or there are more crimes than in the past it is only because the media reports more on them. With the 24 hour news cycle the media is able to report on every little thing that happens, whereas before only important things were reported on.