"I think when you write about another group’s very real experience you absolutely must take time to research and talk to the people you want to write about."
I mostly agree with this statement. A firm understanding of the culture/demographic you're writing about, in addition to be courteous, can have a great impact on a written work. However, I tend to err on the side of giving writers too much freedom with their work than not enough. The point of my article was about critics who believe that authors shouldn't write outside of their identity.
"Otherwise you end up with something that is potentially harmful."
Can you define "harmful"? Countless books have portrayed groups in careless and insensitive ways, but haven't caused any significant damage outside of some hurt feelings. Do you have any specific, concrete examples?