What I'd love to see is a summary of great ways to marry both simplicity and power. Low bar and high ceiling is something of a holy grain in any given application.
Here are a few:
1) 80/20 -- pareto principle should be applied at all times to what is shown on the screen.
2) minimize what is shown on the screen -- on screen = attention. you're telling the user that something is important by showing it to them.
3) progressive disclosure -- if you mouse over or click on something, show more things you can do with it. proximity and action = the user telling you to show them more.
I think that for some user types and in some applications sacrificing capability for simplicity can actually be a good idea in product design. It seems that most humans experience "decision fatigue" when dealing with extremely feature-filled products and find their productivity decreases when using it.
By decision fatigue I mean that it seems that on average, people make worse decisions if they've had to make a lot of other decisions recently. Furthermore, it seems that accepting that a certain option will not be chosen also contributes to this. [1]
Relating this to product design, each new feature represents an additional decision that must be made when a user attempts to accomplish a task where the feature is presented as relevant -- "should I use this feature, or shouldn't I?" Even if the feature is not used, it's presence as an option contributes to decision fatigue.
I agree with Prof. Norman's point that good design helps alleviate these issues by giving us the mental models to avoid considering irrelevant features during interaction. The problem is that both the users of these designs and the designs themselves are imperfect, leading back to the fatigue caused by consideration and decision making about irrelevant details and options.
Maximizing capability is as incorrect as maximizing simplicity. I believe that the ultimate goal should be one that balances simplicity with capability in a way that takes the user's humanity into account such that productivity (whatever it means for a certain product) is maximized. [2]
If you haven't read Don Norman's book, you should do it. It's called "The Psychology of Everyday Things" and it's a wonderful exploration of how to make products easier to use (without sacrificing functionality). The examples are a bit dated since the book is from the 80s, but the concepts all still apply.
My favorite quote is "It's a shame when something as simple as a door needs an instruction manual, even if it's only one word".
Here are a few:
1) 80/20 -- pareto principle should be applied at all times to what is shown on the screen.
2) minimize what is shown on the screen -- on screen = attention. you're telling the user that something is important by showing it to them.
3) progressive disclosure -- if you mouse over or click on something, show more things you can do with it. proximity and action = the user telling you to show them more.