Paul is using the human body as a metaphor for the church. The local church that realizes the ideal here envisaged, is a great church family to belong to. Every person is important; every one valuable. It hardly needs to be said, that the same principle applied to the various nationalities, tribes, peoples and subgroups, would transform human life at large. It is simply not true, that some people are a waste of space. Everyone is necessary.
I'm busy working on my blog posts. Watch this space!