Real time games take a lot more time and money to develop than turn based games. You need a far more robust physics engine, far more complicated calculations, with a lot more glitches and bugs to test for. Turn based game play is basically just numbers exchanging in the background, everything you see on screen is a combination of pre rendered animations and effects. It's a lot easier to do, and if the visuals become a problem anyways, you can easily skimp on them without in any way impacting the actual game play.