It just wouldn't be a myth about Dionysus if it didn't include a little dismemberment. In this story, you've not only got the dismemberment of Pentheus, you've also got the dismemberment of some bulls. Turns out that ritual dismemberment (sparagamos as the Greeks called it) of bulls is thought to have been a fixture of Bacchic rituals. It was said to recreate the way that Dionysus himself was dismembered as a child by Titans and later reborn. This death by sparagamos and resurrection was a key part of the cult of Dionysus.
The myths of Dionysus aren't the only ones to include a little dismemberment though. Lots of ancient religions practiced their version of sparagamos on sacrificial animals. There are also other gods who were said to have died by dismemberment and been resurrected. The most famous example is probably the big time Egyptian god, Osiris, who was said to have been torn apart by Set. His sister and lover Isis hunted all over the world and put his body back together again, and later the higher gods resurrected Osiris as the Lord of the Underworld. (A gloomy post, but alright.)