Knowing when simple is simple enough seems like a bit of art as well as science. But when you know your patrons needs well enough (through great research and understanding), I imagine that's easy, eh?

Gosh, what a rude response to leave on the blog.

The blades do appear, contradictory, I agree.

The reason is this. Occams razor tells us to simplify appropriately - not indiscriminately.

So:
"Always choose the simplest design that does what people need it to do."

Choosing a very simple design that doesn't address user needs would be a waste of time, and a misinterpretation of Occam's razor.

As Richard Collings says above, "if you think the solution is simple, you haven't understood the problem."

If you're only going to have three point, at least make sure they aren't contradictory.

"Making the simple, complicated is commonplace. Making the complicated simple - awesomely simple - that's creativity" Charles Mingus

"For every problem, there is a solution that is simple, neat and wrong" H L Mencken

My view, for what its worth, is that one has to understand the full complexity of the problem first and then try to work out how to find the elegant simple solution.

Or to put another way "If you think the solution is simple, then you probably haven't understood the problem"