Actually I believe it's fairly well documented that that shot is an experiment with using a cg Enterprise model.
The giveaway had to do with the running lights I believe.
Possibly referenced in Larry Nemecek's TNG Companion book and some other places if I remember correctly.
I remember reading the same thing. That it was an experiment, and they didn't like the results, so they never tried it again.
This used to be in the article from Memory Alpha, but was removed for not citing a source. I guess that's where I got it from:
This episode contains one of the first instances of computer-generated imagery (CGI) to grace an episode of the Star Trek franchise. As the Sheliak colony vessel approaches the Enterprise (approximately, 33:18), one of the few exterior shots of both vessels together, the distant Enterprise-D is a CGI model rather than a physical entity. The shot is very brief and the CGI replica is often mistaken for the similar two-foot filming model, however still-frame analysis reveals that the computer-generated Enterprise lacks much of the detail found on even the tiny two-foot model. Because of this, a CGI Enterprise would not be seen again until the first TNG feature film, Star Trek Generations, by which time computer technology had progressed significantly.
That being said, it looks very fake and low resolution. Even the worst shot of the 2-foot model looks better than that. I guess we'll find out one way or another when it's remastered.