Fundamentally the ability to take-off, spin, and land are essentially the same. With bigger jumps a lot of factors become more important. Your timing and speed guages are more important to pay attention to. To throw a 360 over a 15-30 ft. table top will take a more precise and calculated spin and landing due to the fact that over or under rotating will have bigger consequences, especially since you'll have more speed. More time in the air and more distance traveled means there is more time for the flaws in your take off or rotation to show themselves. The most important factor to spinning off a bigger jump is just to have the balls to do so and committing to the trick and being mentally focused. Obviously you will have to have more speed to make the trasition, slow the rotation so that you come around just right with your nose pointed downhill, and try to spot your landing as early as you can and stay focused on it so you don't over-rotate. Ultimatley bigger just usually means scarier for most people.
And flips get more props because you don't see them as much. Yeah, they're not as hard as everyone makes them out to be, but most people just have negative feelings about being upside down while traveling through the air. And all that means for us is getting more mad props from our friends