E-cigarettes are “nicer”, more civilized, and it is “cool” to smoke now, since the problem with second-hand smoke is vastly minimized. Not really smoking, doncha know, but this is a way to play “bad boy” without the coughing fits.
I think marijuana is perceived as the ‘cool’ thing to smoke in high school. The curriculum doesn’t bombard students about not smoking marijuana the way it does tobacco.