Opt In or Opt Out

I had a brief conversation yesterday whilst down in London. It went along fairly classic lines. My question: 'How can we get more missionally-minded Christians to move into council estates and inner city areas?' The response was all too predictable, a wearied frown and a small but perceptible dropping of the shoulders: 'But that's a very special kind of calling...'
The guy should've known better, he grew up on a council estate and is heavily involved in urban ministry with a very significant church. And he was talking to me. But we'd not met before so I didn't chin him.
I'm totally convinced of one simple thing; as long as ministry that impinges on our middle-class comfort is considered somehow 'special' we'll never see 'Thy Kingdom come, thy will be done on earth, as it is in heaven.' As long as we keep acting as if the great commission (that pesky 'Go' thing Jesus said) is something we are expected to opt-in to things will never change. Basically the orientation is as follows: there's a lot of mess in the world and I should assume that God wants me out there in the thick of it unless I am given explicit instructions to the contrary.