Infrastructure is important. I would even be willing to give the idea of eminent domain a shot if it were being used to develop forward-looking infrastructure, not the same old shit.
For instance: eminent domain to build more routes for cars? No. Eminent domain to setup a transnational, high-speed commuter train, capable of traversing the country comparatively cheaply and eco-friendly? I'd think about it.
Point is, eminent domain is only justifiable when it serves the national interest. I don't think building a $300 million military training facility next to a base - especially when it is to be used by a unit that is supposed to be secretive - serves that interest, and neither do super highways or coal plants or any of the other crap they use it most frequently for.