Garry Bargsley explains the utility of the model database:
Below I will outline the model database, which has a unique purpose for SQL Server.
The model database is an empty shell of a database that has the sole purpose of providing a database template for any new User Database created in SQL Server. With that being said, you can make configuration changes to the model database and then expect those baseline settings to be applied to all new user databases.
Read on to see some of the things you can set. I was a bit disappointed in some of the things which model doesn’t apply across to other databases, but it does carry over quite a bit.