I haven't looked at the numbers, but I expect that the rise in HBP has coincided with the sticky-stuff crackdown that the league got serious about a year or two ago. IMO either the balls need to be more grippy, or the league will need to approve certain sticky substances for pitchers to use so they can grip the ball and control their pitches better. Or pitchers need to throw a bit less hard--it's hard to imagine everybody getting on board with that idea though 
)