Configurability, in and of itself, is not an evil, should not be unilaterally abolished, does not cause applications to lose their focus, does not cause global warming, and did not shoot JFK. And I don't care who or what they are, I will flame the everliving hell out of the next person who claims I said it does.
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TOO MUCH configurability, and POORLY-ORGANIZED and POORLY-THOUGHT-OUT configurability, on the other hand, have all sorts of negative impacts on an application.
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With regards to focus, over-configurability has a nasty way of causing feature creep; "well, we want people to configure this, so we should offer a way to configure that and those as well, and that means we need to support option X so we'll have to refactor foo..."
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And in terms of user focus, it also has a nasty habit of distracting attention from what the user is actually trying to do; there are so many applications out there which immediately pop up configuration dialogs first thing after launching, when so many of them don't actually need to do that, and would run just fine for most users with a sensibly-chosen set of defaults.