I agree with this one a lot. It is understandable that people coming from shonen manga will have those patterns in their minds and they will try to find them or see them even if they don't exist in a seinen manga. Even when the mangaka ends season one by bruttaly having the main character get stomped all over the place effortlessly by the at the time antagonist, they still think it will move like your typical predictable shonen.
Now, all this said, the father's total absence is understandably suspicious. On the other hand, Kaneki doesn't even remember him, so we can't see him either since we are always watching through his POV. Then again, Kaneki was 4 years old when he died, and he was his father ffs so how can he not remember him well?? Could be because it was a traumatic experience for the young Kaneki-kun?
And now for some crazy plot twists. I thought about them really well while drinking coffee :kappa
PLOT TWIST 1: Kaneki's father died because of ROS disease. He had it before Kaneki was born and that's why Kaneki was so compatible with Rize's kakuhou. :pogchamp
PLOT TWIST 2: Same as above but he still hasn't died. Wife left him because of the disease and told Kaneki he died. :pogchamp