For instance, Jules Verne's "From the Earth to the Moon" planted the seed for the Apollo Program. As Asimov's work on the laws of robotics planted a seed to inspire future AI development.
Edit: To better make my point, "Robert Manning used to make cardboard rockets... Now he makes real ones."[1]
[1] http://blogs.laweekly.com/informer/2012/04/caines_arcade_vis...
Fiction inspires us to consider new possibilities, it doesn't give us a roadmap and blueprints. This desire to build Enterprise is assuming that Star Trek is indeed a roadmap and blueprints. Did we build the Apollo vehicles based on descriptions of technologies, materials or even shapes by Verne? No.
If you actually look at his roadmap and blueprints, Gen1 through Gen3 have nothing to do with the fictional Enterprise. It's just a catchy name. Only the Gen4 spec gets into "fictional science" territory (warp drives).
All I can see are guys making fun of this guy's ideas because it was originally based in fiction. That is an illogical argument. The man with the plan has put up all the details he can on his website. You can pick apart his ideas if they really are flawed. Why just focus on the fact that his idea was originally a piece of science fiction.