The 35-year-old singer feels critics are overacting when it comes to the 'Wrecking Ball' singer, who gyrates and simulates sex acts during her 'Bangerz' tour, after parents described her live shows as ''soft porn''.
John said: ''I think it's relatively harmless - she's not doing anything dangerous.
''She's just making decisions about how she wants to portray herself sexually and physically. ''It's working for her at the moment.''
The 'All of Me' hitmaker thinks it's difficult for child stars being under so much pressure and people shouldn't be too hard on artists like Miley, 21, and Justin Bieber because they are having to make their youthful mistakes in the public eye.
He told Britain's HELLO! magazine: ''It's hard to grow up in front of the world. Everybody Justin's age makes mistakes - his are amplified because of who he is. That being said, he's got to make better decisions if he doesn't want to endanger his own life.''