It is true that riots have negative consequences for the communities in which they take place, but they are still powerful means of drawing attention to the sorrow and rage felt by members of deprived communities. Riots can encourage real reform, and many have done so in the past.
When a community or people finally unleash the pent-up emotions and frustrations inside of them, the public and those in power are forced to institute real reforms to rectify whatever wrongs and injustices led to the civilians' outrage.
The civil disturbances in the 1960s resulted in the Kerner Commission, which examined the cause of the unrest and encouraged reforms in local police departments.
More minority police officers were hired, civilians could complain to review boards about cases where police officers used excessive force, and officers were obligated to live in the communities they policed.
Riots, with all the violence they inspire and harm they cause, tend to eventually bring communities some significant benefits. The disruption and destruction that takes place in such events is precisely what moves those in power to authorize real change.