Contrary to earlier comments made by Halo 5 developer 343 Industries, using the guns' smart scopes makes your shots more accurate.
Those who were lucky enough to play the limited beta for Halo 5 which was hosted over the weekend have a lot of opinions on all the different changes in the game. But the biggest complaint by far is that that aiming down sights makes your bullet spread tighter, thus improving your accuracy, something which 343 said won't be the case when it revealed the new addition.
As YouTuber Akki n Nyxi demonstrates in the video below, the SMG, BR and the AR all have a tighter bullet spread when used in smart-scope mode.
Of course at the end of the day, beta is just that: a beta, and beta builds do not usually represent the final state of the code. The Halo 5 beta specifically has been made available early in the game's development cycle and many things can and will change.
The beta will be open to everyone who owns Halo: The Master Chief Collection on December 29.