again, taking FSN as the example, i think you will find out that this particular one has a lot of combination of purple prose that is further enhanced by visual effects if you read it through the end. Example you showed is for slice of life scenes, which is kinda nitpicking but an acceptable point. During scenes in VN that does require explicit, enhanced atmosphere such as action scenes and eerie/scary scenes, youll find out that visual enhancement does improve the experience somtimes quite immensely.
i mean
this kind of scenes really doesn shown lazily in both Grisaia or FSN. If anything, both of those oversaturated and transformed what wouldve been a boring narration of slice of life narration into weird quirky comedic in Grisaia and high contrast theme in FSN
dunno about Kanon so I dont know how did you come up with this example based on those 3 you read. Maybe give an example directly quoited from the VN?
The cool thing about VN is like this: in route A, you pick options A to get Heroine A. Then you follo Heroine A story. But then when you pick option B to go to heroince B, you find out things that otherwise wouldnt have happened if you go A route. Choices arent just about getting to the route you want, its also about telling the causal effect of your choices and what would and would not happen due to it. Like a small scale butterfly effect. Of course, some VN do it much worse than the other. I remember Clannad do it particularly well.