Simply because people see huge clouds and think 300 plus watts will provide them, which is crap, the coils you use will have more influence on the amount of vapour, from my stance the only good thing about the stupid high watts is they take more batteries so using such devices at say 40 watts will mean the batteries will last much longer each charge because there are 3 or 4 instead of 1 or 2 batteries. apart from that there really is no point its just way to uncomfortable to use really high wattage. But companaies have grasped the show off element and the competativeness of "look i got 350watts you only have 200 so i am better than you" . Happens with all sorts of things, from tracksuits to trainers, Gold chains, tv screen sizes, the list goes on. It's all like someone trying to brag how big a cock they have, and in truth it's all a load of crap, who cares how much it cost or how big it is, its all about how it works or how you use it nothing to do with how much or how big.