Originally Posted by
neflight86
If you read the manga, or the anime ever gets another season, you'll find they get an entire arc devoted to filling them in (backstory) and giving them sympathetic traits, even having fun with each other. I also don't think they are depicted as brutal, psychotic killers exclusively, even during what was animated.
Is what you desire more swift punishment? Modern media in the last 10 or so years has taken to delaying evil comeuppance for entire seasons of material to tease the audience along and make it more satisfying (see GoT; the villains had their way for 4 whole seasons before their karma came home to roost, or started to). This is shounen anime, they (the bad guys) will either lose or lose and become allies by the end of it, no doubt in my mind. If their loss and punishment isn't up to your particular requirements for cruelty, well... I don't know if there's any helping that.
To be clear, I'm not in love with JJK as a whole, but I think villains are one thing it does very well.