Laptops in games normally serve one of a few different functions:
With web cameras being more common in real life, they have turned up increasingly in video game laptops as well. This gives the game developer a way to add character to what would normally have been a faceless voice at the other end of a headset.
In older games or those set in the past, the player could be given a mini-game involving lockpicks and deadbolts. With the changing times, those games more often involve laptops and keypads.
Even with all of the technology available today, laptops are very often nothing more than a widget for the player. "grab the briefcase" has been replaced with "swipe the laptop" as often as not. And if there does happen to be a briefcase involved, there's almost certainly going to be a laptop full of juicy secrets waiting inside.