Full pax, full baggage, full aux tank, 300nm run, so you know its going to be light enough to land, it just seemed easier to run it down the runway to get through translation without worrying about engine and transmission limits. And to hell with OEI, we'll just operate like any other Class 3.
Otherwise, running takeoffs may be done if you are taxiing towards the helipad, you call tower early 'cause you expect a delay in takeoff clearance and dang, they just come right back and say "cleared for takeoff". Now you are already taxiing at about 15-20 knots, into wind, with a long taxiway ahead of you. Are you going to stop, and then pull into a hover, move over to the helipad, the pull even more power to takeoff? Or just pull a little more collective while you are already rolling and smoothly transition to flight?
One other case for running takeoffs is if your takeoff area is littered and you want to get into the air with the least amount of FOD risk. Hovering only helps to generate a tornado of styrofoam cups, plastic bags, wrappers, paper, etc. Your compressor will love you.