If you don’t need them, you don’t need them. People use them in different ways. For example, at my house there is a motion sensor at the entrance to a bedroom.
I have a variable schedule and go to sleep at different times on different days. When I go to sleep, I change the mode for the house to “asleep.”
During the day, triggering the motion sensor doesn’t do anything.
In The evening when the Mode is “night” then triggering the motion sensor turns on the overhead light in that room.
Once I go to bed, I change the mode to “asleep” and then triggering the motion sensor does not turn on the overhead light, it just turns on a soft night light on the wall.
People use “home” and “away” in many different ways. Not everyone uses Geo presence. For households with multiple people, the first person of any of the family arriving home will typically change the mode to home and then the second person arriving might see a somewhat different pattern of events than if they were the first one arriving.
Lots of variations. But if everything you have set up is working the way you want it, there’s no reason to throw modes into the mix. 
The following thread has a lot of different examples of how people use modes. (This is a clickable link)