Re: Karbala
^The Prophet (SAW) might not have made it obligatory, but anyone would weep after listening to the events that took place in Karbala and that's why Shias weep and do matam.
And as far as the topic of matam, every group of people have their own way of doing it, whether it is a normal beating of the chest with their hands, or the blades and chains...it's not that difficult to understand.