The Sun moves around, while I am in a room. It might be high up when I enter a room, but after a while there may be clouds or it may have set.
When watching a movie one may dimthe light. Once finished one may need more lights.
When going to bed I may want to switch all lights off. When getting up it may need some extra light.
A switch on the door is nice. More switches is better. Being able to control from anywhere may be even nicer.
So I grab my phone, open the homeassistant app, and mess with the settings on my light, or use homeassistant through my browser on my desktop. No yelling at a computer needed