Rich Benner has some thoughts on configuration:
By default, SSMS does not show row numbers next to your code. That’s not a huge issue when working with smaller blocks of T-SQL. However, when working with larger problems and/or collaborating with colleagues, being able to refer to a row number is invaluable. This is especially important for us here at SQL Solutions Group when we’re in meetings and looking at code. Being able to refer to a line number on somebody else’s screen makes the world so much easier and less confusing.
Line numbers being on should absolutely be a default setting in SSMS. I can’t think of any reason why you wouldn’t want line numbers on. Rich also looks at other ways you can customize the look and feel of SSMS, such as map mode for the vertical scroll bar, organizing pinned tabs, and more.