If a new Constitution were to be written today, what reasons, other than those cited in the Preamble, would you list as reasons for writing a Constitution?

Clearly if you are asking this question you don’t understand the Preamble so I’m going to list the reasons first:
1. Establish justice
2. Ensure domestic tranquillity
3. Provide for a common defense
4. Promote general welfare
5. Secure the blessings of liberty to ourselves and our posterity

So, in my opinion, these are ones I would add if I were to make the Preamble.

We the people of the United States order a perfect Union to insure...
1. Police brutality is just as bad as brutality against police
2. The elimination of wage gap between races and genders of man and woman
3. The union to unite and adore their country; to hate the government instead of the country

Use the formula: (n-2)×180, where n is the number of sides(18-2)×180= 28800, now this is the full exterior angle of 18-gon so you divide it by 18.28800÷18=160