Simply assuming that the proper allocation of resources is easy in this or any other industry is wishful thinking. If drugs have any substitutes the demand side already goes from easy to hard. When drug treatments can cost tens or hundreds of thousands of dollars we have more demand for medical treatments than we have supply. Even the concept of providing drugs "at cost" is complicated because costs vary not only with the price of inputs but with amount supplied.

On the supply side the inputs for the pharmaceutical industry aren't infinite.

Whether it's chemists, chemicals, warehouse space, machinery, or time all of these things are rivalrous. When you put a chemist on one project you take them away from another. If you put a chemical in one drug you take it away from another. If you make a factory produce one drug it stops producing another.

In order to solve the problem of maximizing the benefit of the resources being used we can use a market that uses prices and profits to coordinate itself, or we can have a group of really smart people trying to reason out what is needed where. Markets are historically good at solving this type of problem, bureaucrats are historically bad at it.