I ran across this today as well… this is true.. too much planning and rigid guidelines can lead to a poor solution. I am not minimizing the importance of planning, only the scope.
Projects fail all the time because we unwittingly bake the end solution into our initial objective. Rather than enduring an uncomfortable (but highly necessary) period of ambiguity, we fall into the trap of limiting our creativity by setting a project goal that is too narrowly defined from the start.