Of course, that's half the point. New towns have to be built on unspoilt land, so to speak. But the problem is that the Government's also promoting these new towns as a solution to the affordable housing dilemma. They're meant to help young, first-time buyers get on the housing ladder. Yet - without any disrespect intended to to Coltishall, Imerys et al. - young people want to be where the jobs are. That's why there's so much internal migration to hubs such as London, Birmingham and Manchester.
So, either the Government expects these first-time buyers to all work in Cornwall, or they expect them to commute. If it's the latter, then the Government had better start thinking about improving road and rail links - not something they've excelled at in the past. Besides, just imagine the carbon footprint of creating new infrastructure, and of the cars that will travel to-and-from these Huxleyan eco-towns every day.
It's another case of the Government tickering with the supply-side of things, when some demand-side reforms would have achieved better results. If you want to help young people, then a good start would be to get rid of the prohibitive stamp-duty charges that first-time buyers face. Then they might be able to afford housing in areas where they want to work.