There is a class of systems that offer rapid feedback to the operator, that is, an adjustment in the way they are controlled is very quickly reflected in the output of the system.
Take driving, for example. You press the accelerator pedal (for good reasons I've stopped calling it the "gas" pedal) and the car goes faster. You turn the steering wheel a little and the car turns. For safety reasons, such a rapid feedback system is so natural that it's necessary – it needs to be as natural to our instincts as possible (so that, when, say, a cat jumps out on the road, you can swerve and not hit it). But safety reasons aside, it's also a great way to allow people to become good drivers quickly (you could imagine an alternative way to control a car, for example one in which you point to where you want the car to go. While terrible for many reasons, such a mechanism would probably take much longer to master).
I think this explains why people find it relatively hard to play golf well – the feedback is painfully slow (in fact, it's so slow that special vehicles were invented to try to make it faster – or maybe it's because those playing golf hate to walk – another reason why golf isn't really a sport).
This also explains why an RC helicopter is more difficult to master than an RC car (I think more so than the fact that a helicopter involves more complex controls).
It's useful to use this principle when designing really any kind of system. For example, wouldn't kids find it much easier to learn to play the piano if the correct next key were a little easier to press (or, if that's too easy – i.e. would make people lazy and therefore prevent them from learning – at least all notes of a particular musical key, like B flat, were a little easier to press).
Note that it such a system doesn't necessarily have to be natural in the sense of being an extension of our muscles or senses. Cooking (I mean preparing the entire dish, not figuring out that you've burnt a steak) doesn't offer a particularly quick feedback. Fortunately, its quality is fairly insensitive to the inputs (it takes a lot of mistakes--or a big one mistake – to make a dish taste awful) but we'd be much better cooks if ingredients changed color based on the amount of salt we added.