Why open API is better than closed

The other day I was showing a friend one of my latest downloads (ShowCam) on my iPhone when this other guy 'bursted' - Hey...I don't get it, all you iPhone owner talk about downloads and how people can build what ever they want for that phone. Well (now with a broad smile) this Nokia of mine has ALL of it built in from scratch. I started to explain but understood by the expression on his face that he wasn't getting it so I gave up.Here's a great list showing tons of add-ons for Flickr. I bet my best Iron 5 that Nokia wouldn't have thought about all this from scratch.All because of Open API.