The idea and most of the initial development was by Pike, Ken Thompson and Robert Griesemer, and their explanation for the simplicity of the language was that no feature was included unless all three of them could agree it was necessary. Thompson has since retired, others have joined the "core team", and Pike doesn't seem to be that active anymore in terms of actual commits - however he may still have an active role in guiding the development, I'm not following the development that closely, so I can't tell. But the way I understand it, it's more of a team effort than a BDFL situation...