This past Christmas my parents gave me a day calendar of "The Stupidest Things Ever Said". A week ago, the day's quote was from a sign posted on some door somewhere:
"If door does not open, Do Not Enter"
Should I be concerned that this sign makes a lot of sense to me? I know, I know ... the funny thing about it is that if the door doesn't open, then you can't enter. Thus there is no choice in the matter.
But choice is at the very heart of user experience.
I consider a very analogous web design (that is getting more and more use) - the grayed-out button concept. You'll see it any time you install new software on your PC. There is usually a set of software terms that they want you to agree to before you are allowed to play. So they show you a big scrollable legal text block and a 'Continue' button at the bottom of the page. But the button is gray, and clicking it yields no action. Only when you notice the small check-box above it that reads "I agree" and click it that your continue button becomes active.
But suppose this were the first time you stumbled upon this design? You might think there was something wrong with your PC. You might think that there was something wrong with the software. You might think all kinds of things, because there are too many possibilities for something being broken or wrong.
Telling the user that the button is intentionally deactivated is vital. They have to understand what is happening in order give their acceptance. Otherwise, they are lost and the software goes unused.
A good rule of thumb is to bear in mind that nothing is universally clear. And when a user is on a mission to get what they need, sometimes they need a little extra help. Even if it means stating the obvious.