I have my own personal experience to add to this topic.
Here in Sioux Falls, SD, there are two full-sized bronze casts of Michelangelo's David & Moses. They were given to both the City of Sioux Falls and Augustana College in the early 1970s by Mr and Mrs Thomas Fawick as a gesture of thanks when he was a struggling inventor here in the early 20th century. Augustana strongly preferred Moses to be placed on it's campus. David very nearly didn't come at all, as local religious conservatives rallied against the perceived indecent, homoerotic nude. Eventually Sioux Falls did accept David.
I decided to create models of Moses & David. I know in the case of Moses, over the course of a few hours, I snapped over a thousand or more photos, and nearly as many for David.
I tackled Moses first since I was able to get much more of him than David. I posted screenshots of my progress via Twitter and Google+ and finally uploaded my finished, crude first try of Moses to Thingiverse.
Shortly after that, a representative from Augustana contacted me and requested that I take Moses down immediately and to contact anyone else with a downloaded copy of my model and inform them that they should delete it. I was surprised and disappointed. I asked for the reason. She informed me that Augustana's legal department considered Moses a copyrighted work.
I tried to work with her and the elusive legal department that would never directly contact me, sending them relevant links noting that courts had already set a precedent that any art in the Public Domain that was precisely copied or replicated could not be copyrighted again, not unless the copy was substantially altered to differentiate it from the original.
I contacted an attorney for the City of Sioux Falls and she mostly felt that photography of Moses and David was perfectly fine, but if anyone attempted to sell their photographs or transform them into models, that a copyright or intellectual property of some sort was being violated. All this after I sent the links to the precedent already stated in another court case.
Both bronzes are in public view. David stands outside on city land in Fawick Park downtown while Moses stands outdoors on the campus of Augustana College.
Maybe I went about it all wrong, but I also reminded all the parties involved that for better or worse, photogrammetry is trickling down to the consumer level and it isn't a matter of if, but now just a matter of when. I was essentially asked not to do any more modeling of anything owned by the city, irregardless if it was on public land and in the public domain.
I'm still photographing and working on my models, but I've found I have to be a little more circumspect when I'm trying to capture enough photos to model the odd building or landmark.
I personally think both Augustana and Sioux Falls are in the wrong and probably aware of it, but the only reason I've ever heard that probably comes closest to why they objected to the modeling is the fear that they would no longer control what is done with my models. The Augustana representative told me that the college was uncomfortable that a person could replace Moses' head with another or alter my model in such a way that it would look badly or disrespectful.
I contained my knee-jerk response to remind her of the First Amendment and calmly told her that the very thing that Augustana was concerned about had been going on for decades with other public domain art like the Venus de Milo or Statue of Liberty. Their artistic integrity hasn't been hurt by the many different ways they've been appropriated and making them accessible has probably actually increased their popularity. Surprisingly, for a liberal arts college, they didn't seem to be aware of that aspect and they weren't having it. The only other thing I can think of is they're losing sleep over the idea that someone could take my models and improve on them and make physical copies to profit from. I personally don't mind and think the world could do with more beautiful art.
So have I opened a Pandora's Box or is this more about the city and college making a mountain out of a molehill where they don't have a legal leg to stand on?