Quote - Actually, this isn't what the Court said at all;  In this Case, Meshworks was contracted by Toyota to produce 3D models for a single commerical. These models were registered with the Copyright Office.  Even though they were licensed for a single use, Toyota continued to use the models without paying the Artist.  The Court ruled that an unadorned mesh of an actual physical object lacks the requisite degree of originality for copyright protection, and is therefore not copyrightable.

Take another look at the decision.

"While fully appreciating that digital media present new frontiers for copyrightable creative expression, in this particular case the uncontested facts reveal that Meshwerks’ models owe their designs and origins to Toyota and deliberately do not include anything original of their own; accordingly, we hold that Meshwerks’ models are not protected by copyright and affirm." 

This pretty clearly is addressing Meshwerks' models in particular, and not 3d meshes in general.  It does not say "all unadorned meshes are not copyrightable".

Quote - The issue of derivative works was not dealt with, (and is not even mentioned in the body of the ruling)...

Yes it was:

"In due course, defendants moved for summary judgment on the theory that Meshwerks’ wire-frame models lacked sufficient originality to be protected by copyright. Specifically, defendants argued that any original expression found in Meshwerks’ products was attributable to the Toyota designers who conceived of the vehicle designs in the first place; accordingly, defendants’ use of the models could not give rise to a claim for copyright infringement."

This is the definition of a derivative work, and also see footnote 7.

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