The people complaining see this as stealing and think that the people doing it should be punished. But aren't we all guilty of copying others ideas. I am for sure, and especially in my art. I take someones idea and use it in one of my pieces. Even famous artists are guilty of this as well. It just happens that someone takes an idea, improves on it, and makes it their style. Da Vinci wasn't the first to paint a portrait, Van Gogh wasn't the first to use oils, it just happened they were good at it.
There is a line that needs to be met which is taking someones art and not giving the artist credit for it. People have taken photos of people's art and posted them online and didn't give any credit to the artist of that piece. They end up making money of a of a photo and the artist gets the short end of the stick. This in my opinion is downright wrong and is stealing in my opinion. I understand taking an idea and crediting the artist but when you try and claim a piece as yours... There needs to be something done.
Another thing people have done is, is taking a piece and adding something to it. They still give credit to the original piece but do there own thing. Critics find this outrageous as it is seen as ruining someone's work. The L.H.O.O.Q. by Marcel Duchamp, has been known to this controversy. He took a Mona Lisa print and added a gouty. Critics hated it as it ruined the Mona Lisa and blamed him for it. He made this piece in 1919 and it drove people mad. But in 1883, artist Eugene Bataille made La Rire. A print of the Mona Lisa with a pipe in her mouth. So this idea of "ruining" art was around before Duchamp. Also the artists credited Da Vinci and the piece itself.
Art is very controversial. Especially when people don't understand that art is something that is stolen, reused, and mimicked. This is how artists improve and make pieces. Sometimes people go to far and completely take another's piece for themselves. The way people must look at it is, when you put something such as an art piece into the media, you do not own it anymore. It is the public's.