If you care so much about getting info of the world before 2077 before the game comes out, you would read a wiki and read about Red. This book is most likely just a lot more info about everything you see around 2077, so if you liked the game and wanted more details about the world you just played, you would get the book. In other words, tons of spoilers for the gangs and most other stuff.The general public is not going to go on a wiki for background details and certainly won't be playing RED. I think you may be missing the point of this book
I want to know about stuff in 2077 also, but I would rather get my first impression when playing the game and seeing cool people and other stuff for the first time at that point and if I want more I just get the book. Why would you want to know everything beforehand? Isn't it better to experience it first?
Guessing its personal preference, but why ruin it for the people that don't want it.