The Australian historian puts the blame for lack of preparation on the higher commanders of which the most obvious man to blame was General Wavell. We would be tempted to blame the man at the top, Winston Churchill,
The lowest level commander General Weston, had very immediate issues to deal with. There were about 50,000 men who had been evacuated from Greece. They needed accommodated and fed. The first soldiers from Greece along with "civilian refugees" came to Crete starting on 23 April. Larger numbers arrived on Crete starting on 25 April. They often needed basic supplies, such as blankets and tents. Men were forced to sleep on the ground. They had their clothes and "great coats". The men were taken to areas in groves of olive trees. There was nothing for the men to do but rest. The men were used to drinking beer. The strong Greek wine was a problem. Combat units landed as complete organizations, had no tools to use to dig "field works". They had to use petrol tins for cooking. There was an intent on having new arrivals join other men from the same organization.
This is based on the account in "Greece Crete, and Syria" by Gavin Long.