Nasu decided to write CCC as a second attempt at HF. HF itself turned a lot of people away from Sakura.

Shirou decides to stop being a nutcase idealist and save someone he loves instead of trying to save everyone, the truth about the grail is revealed - that it's not only corrupted by all the evil in the world but the servants are just fuel to power it, and even if it could grant a wish it would just interpret it in a destructive way. The only thing that drags it down is the slow first part and Sakura who has no personality besides wanting Shirou's dick and penis worm rape trauma.