My takeaway from it was that people are generally nonviolent, with a few (taxonomised) exceptions.
(My meta-takeaway from it is that poor intellectuals in the US have it much harder than rich intellectuals, but can still pay their dues and eventually make their own way.)
Here's a quote from the book: "We had an inmate in custody who had cut open a baby with a tin can lid and raped the wound. If someone can do that, do you think he will hesitate at all before gouging your eye out or biting off a finger?"
More generally, I think there's a difference between "meditation on brutality" and "misery porn", and that the latter sometimes gets dressed up as the former.
Edit: I wanted to demonstrate the stupidity of this question: "How is Meditations on Violence supposed to convey the brutality of life as well as the other titles?"
The quote is not representative of the general tenor of the book, but it is representative of why that question is dumb.