Let me be the one billionth person to use Apple as an example of good design.
Every time Apple releases a new version of one of their products -- say the iPhone -- I think "Wow... this is even more iPhone than the last iPhone." Apple knows exactly what their vision for the iPhone is (simplicity, ease of use, elegance and power in your pocket, optimized for mobile use), ruthlessly guards it and lets it inform every design choice they make.
Not everybody does this, I think basically because not everybody knows what their product is: and particularly what it is to the end user.
Take Facebook. I think the end user sees Facebook as a tool for finding out what's going on with their friends and then connecting with them. I think Facebook sort of gets this, but mostly sees Facebook as a platform to show you ads.
That's how I explain something like the recent changes to the News Feed, where it's now based on a Facebook-controlled algorithm that selects what stories filter to the top. That just seems like it's adding noise to the whole seeing what's going on with your friends and connecting with them thing.
You know what algorithm I want for my News Feed? The one that most directly connects me with my friends? It works liked this: ORDER BY created_time DESC. Show me all my friends' updates with the most recent ones first. You remember that one, right Facebook? It was the one you had back before people started complaining about the changes you made to the News Feed.
I know Facebook needs to make money and they do that by selling ads. More power to them. And any change where Facebook has more algorithmic control over what you see gives them more ability to steer you to the content they want you to look at. But I get why people are pissed off. It flies in the face of what they want and value about Facebook's brand.
To be fair, sometimes a change that makes sense for selling ads also creates a good experience for the user. I've had a chance to see a developer preview of the new Timeline feature and I think it's awesome. It really does let you see what's going on (and has gone on) with your friends in a new, interesting and spiffy-looking way.