According to the received wisdom, one way to ensure that a communication is simple is to reduce the number of elements in it to the absolute minimum. There's a popular diagram that begins with a layout of a standard car ad. All possible elements - headline, subhead, visual, body copy, logo, stapline, starburst etc - are included.
The elements are then gradually removed, until only the picture remains. Even in layout the point is clear. The last frame is considerably more impactful and engaging than the first. Why? Because it's "simple".
But in practice, this economy of style has a tendency to make the experience less simple for the person receiving the communication (I'm not saying this is a bad thing; indeed, ads are generally the better for it).
This isn't an ad, it's a T-shirt design, but I think the point holds true:
The shirt withholds a crucial piece of information: that the Second Amendment is the right to bear arms. If that had been added as a subhead, the layout would have been more complicated - less graphically "simple". But it also would have been easier to understand - "simpler" from an interpretive point of view.
Of course, if the shirt were more explicit, it wouldn't have been as funny. Indeed, I suspect most Americans, who automatically know what the second amendment is, would think it pretty lame (it is, after all, a fairly obvious pun). But when I saw it for the first time I had to think for second, and it's that extra second, that wafer thin layer of obscurity, that made me laugh.
I'm not an Art Director. In fact, I'm renowned for my lack of aesthetic sensibility, so having a clean layout isn't something I makes me feel funny in my special place. But, just like my AD and every other creative I know, I've been known to spend hours crafting a concept so there's just enough information in it to allow the audience to complete the meaning themselves, but not so much that it patronises them (one of the strengths of this approach is that it allows you to say things you'd never say explicitly).
That's often where we part ways from clients, who when they say "simple" mean "I want everyone to get it".
Of course, as the example of the T-shirt illustrates, if you spell it out so clearly that everyone gets it, there's often nothing left to get.