Even cartoon violence goes too far sometimes. As you dice up cops and urinate on dead civilians, it doesn't take long to realise that the violence in Postal isn't funny or pushing boundaries at all - it's boring. With no background music or context to your killings, the violence becomes more uncomfortable as you realise there's no point or reward to the slaughter. Because it's not fun, the extravagant killing makes you question what type of person you are, as youconclude you could be doing literally anything else with your time.
Even though the likes of Postal and Hatred are made to thrive off controversy and to push buttons, it doesn't automatically make them significant pop culture "satire" or social commentary. More often than not, games like this chase the spotlight by being as reprehensibly violent as possible - which is all well and good if your game is actually fun. But the Postal series isn't; it's mindless anarchy executed in the most boring way possible.