I think it's important to note that there can be all kinds of planned economies, including capitalist ones even, and ways of doing planning. I (and I would imagine a lot if other Marxists) are in favor of an economy planned according to democratic centralism. Everyone would be contributing in some way to the planning. In Marxist planned economies, it isn't the top dictating to the bottom. It's from the bottom to the top and the top to the bottom. An economy run on the mass line