Along with 12 new 3D buildings in 21.7, you can now see the taxiway lines at the airport you are at or controlling at. This addition helps the pilot plan they’re taxi route with ease and expand the realism.
It also helps them with pushback where there are more than 2 taxiway lines in the terminal to pushback on.
This new addition also helps the controller in many ways. For the ground controller, they can now give progressive taxi instructions easier without having to guess where the taxiway lines are. The ground controller can also tell when there is a ground conflict approaching easier by seeing exactly where the 2 aircraft may interfere.
For the tower controller in the other hand. They can analyze the airport and where the hold short lines are located, this lets them know where the pilot is easier and avoid take-off or landing conflicts between a departing or arriving aircraft and an aircraft holding short awaiting for departure.