Table not getting created under dbo schema
The schema that will be used when schema is omitted will be the default schema of the database user.  Therefore, to have dbo schema have the created table without specifying, you'd have to set that database user's default schema to dbo.

Server-wide setting?  I don't think so.  But you could write a query to convert all database users in a particular database to their default schema changed to dbo if that's what you so choose.