creating database - what is the real purpose of additional parameters

 Hi all, 

I'm looking at CREATE DATABASE at Microsoft docs https://docs.microsoft.com/en-us/sql/t-sql/statements/create-database-transact-sql?view=sql-server-2017 

and the very first example says that it is enough 

USEmaster; GO IF DB_ID (N'mytest') IS NOT NULL DROPDATABASE mytest; GO CREATEDATABASE mytest; GO

(then verify that it exists).

Also on that mentioned link you can see more examples using additional parameters. 

So... help me please to understand, what is the real purpose of those additional parameters and why exactly should someone need them. Briefly. Please advise.