But there is a considered and logical argument behind the parody of 'socialist cook books' and so on.
The reason it is wrong - or not so much wrong as empty, formalistic - to draft plans for the future socialist economy is that the socialist economy is conceived of as the realisation of the popular will in the formerly closed sphere of production; and to substitute a preconceived plan for the popular will is to deny the popular will.
All talk about what socialism would be like is bound to have a very speculative character, because we only anticipate what the people of the future might see as important. Maybe the seas will be made of lemonade (as Saint Simon joked) or the public toilets of gold (Lenin).