From what I'd heard, it was more of a case of FASA got permission, but asked people who, it turned out, only
believed they had the right to give such permission(some smaller company(not HG), I think it was whoever was importing Robotech merchandise at the time).
There was never any actual judgment barring FASA/CGL/Topps from using the art, but until last year...er, two years ago now, they simply stopped using any out-of-house art(including some completely original art commissioned from smaller outside companies(see: much of TRO:3055)), to avoid any possible future conflicts. Now only the original Macross-based art is considered 'Unseen', and a few were already so significantly altered(the "Ost"-series 'Mechs), that they're not considered part of the batch any more.
EDIT:
There was a confidential settlement that ended the original court case, which was apparently overlooked or forgotten about.
Late EDIT2: On thinking/
checking again, it was mostly Clan Mechs from TRO: 3055 that were Unseen due to association with VMI, plus a few Unseen-derived designs, though some were considerably altered to the point where you'd have to be told what they were supposed to resemble.
