The iPhone comes with all the basics out of the box. And they are all perfectly serviceable.
Seriously. I could use the built in calendar for my scheduling and the notes app for the writing/capturing stuff. I don’t need Twitter or App.net. All of this extra stuff is “nice to have” not “need to have.” We would all do better to remember that.
I pretty much follow the same philosophy. I don’t install third-party apps just for the fun of it.