Mother Jones reports on Penn’s ouster:
Penn was (and still is) an unpopular figure. He was disliked by wide swaths of the progressive movement because he ran a multinational corporation that had its fingers in a lot of dirty pots. Burson-Marsteller and its many subsidaries have lobbied for and represented tobacco companies, oil companies, Union Carbide, and Blackwater, among other clients. Penn became a particulary easy target for criticism when it was revealed Burson-Marsteller specialized in busting unions.
Penn was no more liked within Hillaryland, for both personal and professional reasons. His imperious nature and unwillingness to accept responsibility for failure rubbed many Clinton loyalists the wrong way. His reliance on data and his insistence that the campaign need not “humanize” Clinton produced mounting criticism with each primary loss. Blind quotes from top Clinton aides criticizing Penn are usually an easy get for Washington’s top journalists.