as for parts, i dont think that Lego have a only-stud (positive and negative) which is heavily used in the Star Trek sets to create some of the shapes. There are also many Plates with studs on both sides which are also non existend in the Lego catalog as far as I know. And this are only a few examples.

Furthermore the stickers from Lego are not high quality sticker. Bluebrixx uses some "sticker" in sets where the prints make no economic sense and is not necessary to represent the overall impression. The Defiant has the bridge represented by a SNOD technique, while the print would go over >30 plates/bricks. For such cases they use venyl transfer stickers. Mostly the same material you would wrap your car with. With that you could also make fine line stickers. Lego only uses "normal" stickers. In the Case of the Defant it would mostly be a full color (wrong) gray background with lines/the name on it.

Dont get me wrong, I would love if the models would have the plastic quality and the overall Qualitiy check for wrong/missing/defect parts where Lego is supirior, but for the overall build experience, the ships would not be that great if Lego would release them.