The Middle Age mindset shows through in Lucifer's punishment. Although God sent Lucifer to hell, it was Lucifer's choices that caused God to make that decision. Namely it was the choice to commit one of the Seven Deadly Sins. In the Middle Age mindset, this is the worst thing a person could do. Lucifer committed the greatest sin, pride. Pride itself may have been accepted for a short period of time, but Lucifer saw himself as greater than God and that was the worst possible sin to commit. Therefore, in this mindset, it makes sense that Lucifer was sent to the worst circle of hell. Also in this mindset, your choices in life decided your fate after death and no amount of apologizing or grieving after death was going to change that, so it seems wise that despite Lucifer crying for centuries, he is still trapped and in fact is only more trapped the more he cries. They also believed in symbolic retribution. This caused the intense symbolism of the act of chewing, his looks, and how he is trapped make even more sense to people with this mindset. Due to this, although today we may see this punishment as excessive after so much grief and pain is shown, Lucifer's punishment in Dante's Inferno makes perfect sense in the Middle Age mindset.