I think the problems is that with a lot of people for such a change in perspective to come off well in gameplay either the gameplay segments(not just the character gameplay) have to be significantly different all the way through for a full route experience, or the route should be heavily abridged to deliver the new story and context.

Personally for me it also doesn't help that most of the context regarding the enemies that you get in the second route feels like its too heavily implied and foreshadowed in the first route that it feels too obvious, so instead of a big shocker it just makes the first route feel less engaging for me cause Im just sitting thinking "Oh boy in route B I wonder how this boss will have a super sad backstory and make me feel guilty". Though that might work a lot better for other people, it could just be that I dont really mesh well with some of Yoko Taros storytelling choices. The one time I did really feel it worked well though was the wolves story in Nier Replicant, that added context did change how I looked at that part.