72 FPS might be easier on the eye than 30 but if you just brought someone into a room and asked them to guess the FPS on a game you were playing they wouldn't be as accurate as you think. The reason 60 FPS is better than 30 FPS is because the turns are smoother, and that's a big part of a game like ESF where you're cards are required to redraw backgrounds and character models at all different angles at any given time. We notice skipped frames on a flat immobile monitor more easily than we do when we turn in real life because our vision tends to blur anything we aren't focusing on. A video card tries to keep every texture sharp all the time, so when you turn fast with 30 FPS you notice that the screen misses a couple of frames and it bothers your brain a little. At 60 when you turn you skip less frames because you simply have more being layed down. When your frames get out of control and you don't have v-sync on to cap the rate and smooth them out for you your card doesn't know where to put the data so it puts more than one image down at a time and yadda yadda. I know Cuc already said this stuff I'm just trying to see if I can provide a different perspective for explanation.
Anyway, your brain can tell the difference between 60 and 30 when you're turning and your brain is focusing your vision on everything on the screen (since it can't focus on just the individual lighting mechanisms that color textures), but if you were just watching a render of something or sitting still you couldn't tell. That is where the arguments get confusing. Feel free to correct me as you find errors in what I'm trying to say.