Looking at my WR, it pretty much is perfect, which means I can't be the only one. So it only stands to reason that as long as they follow the same protocols with CG as they did with WR, that more than a few fans will get outstanding if not perfect CGs as well. And if some slight paint issues or the odd missing accessory are the only problems with CG's production, then I'd gladly take one of the "flawed" ones if that means other fans get great ones.
Nit-picking the WR has pretty much zero bearing on CG as far as I'm concerned. I mean are we MotU fans, or not? Don't we want a (worst case scenario) so-so Grayskull more than we want no Grayskull at all? I'm usually ALL FOR holding Mattel's feet to the fire and wanting them to be accountable, but only when we actually have the problem to complain about. All of this cart-before-the-horse prognosticating on "what if" problems with CG isn't doing anyone any favors.
The 4H never had anything to do with the RETRO REAL GHOSTBUSTERS figures.
I'm talking about the MEGO style dolls.
Regardless, the 4H themselves are huge MotU fans (so much so that they unsolicitedly pitched not only the MOTUC figure line, but the vehicles as well!) and as they say themselves have been chomping at the bit to sculpt the Castle. The Ghostbusters MOVIE line on the other hand, they specifically said they were too busy to keep doing it, and no way were they gonna drop either DC or MotU in favor of GB. So the 4H sure as heck wanna do this one right from start to finish. And Mattel has no incentive to make it otherwise. In fact, there would be a HUGE fan backlash if we learned Mattel let in-house people do extensive CG alterations or creation in favor of the 4H. Mattel knows this.
Also, you're assuming a lot saying the very best design staff was replaced with a vastly inferior one. For all you know, it could be the exact same people and those "wrong" changes were requested by the licensor. (Which, funny enough, is what happened with the movie GB figures the Horsemen DID work on, where their cool head sculpts were dumbed down during the approvals process... yet another thing we don't have to worry about with CG since Mattel owns MotU.)
I'm sorry for BTTF fans that the Hoverboard didn't turn out as well as expected, I really am. But the Hoverboard and CG are total apples and oranges. The Hoverboard has a very specific design in the movie, with no other "interpretations" from any other source. There's one source and one source alone, so it's easy to compare A to B and spot the differences like a kid's activity book. But even if there were wiggle room to make a different version, there's no such thing as the "4H of BTTF" who are as proprietary to the creative vision of BTTF prop replicas as the 4H are with MotU collectibles.
So where the Hoverboard can categorically be "wrong" compared to the source, however the 4H decide to make Castle Grayskull will automatically be "right" because it will be their version. You might disagree with their take, prefer Filmation, or whatever. But it can't be a wrong version, simply the 4H's version.