IMO,Alot of people(mainly on other forums) in this hobby like to "follow the herd",they buy the most expensive stuff they can so they can show it off.The HQI fixtures are attractive and small so that is prefered by some who dont want to build a canopy/hood..But mainly,most people dont know the facts about lighting and how different bulbs perform on different ballasts.If u like,i can show u some spectral analysis charts/studies of mogul bulbs and of DE/HQI bulbs.