Obama issued an executive order to close it on his second full day in office. Congress blocked it. He continued trying to close it throughout both of his terms, and Congress continued to prevent that.
Not any hospital but one run and staffed by doctors without borders. A hospital which was specifically on a non-target list and was known by the US military. The supposed mistake is akin to accidentally dropping a bomb on one of your own bases. Accidents do happen but something like this is a huge failure in US military procedures.
