There were a lot of people who were very happy with Tokyo Ghoul season 1. A lot of people were so excited for the next season but they became greatly disappointed when season 2 ended. It seems that there were a lot of issues that were not considered to be resolved at that time.
A lot of fans of Tokyo Ghoul have decided that the next season is not worth it so they would rather not continue watching anymore. The characters of Tokyo Ghoul are still strong but the storyline is not as good as the first season any more. The animators of this anime series wanted to try something different and people did not like it.
The first season of Tokyo Ghoul was very popular among fans and nearly everyone was excited about the second season of the anime. Unfortunately, season 2 ended up having a lot of issues and many fans reportedly hated the second season.
The reason is fairly simple: Season 2 of Tokyo Ghoul had strong characters with interesting backgrounds who were easy to connect with but the story line left a lot of fans wanting more. Rather than a direct manga to anime adaptation, the creaters decided to do something entirely different and it was a risk that did not pay off.