Agreed.
I think they are going for the Netflix Marvel feel except the use of violence and lethal force and debates around these are constant issues in the Netflix series. With the exception of Punisher, the Netflix heroes have utilised violence but have been hesitant in using lethal force (although DD almost killed someone in Season 2). With the exception of Beast Boy and Raven, we see all the Titans burn, shoot, slice and snap the necks of street mooks.
Heroes can use lethal force but the way it's displayed by the Titans in the trailer just feels...off. It's just trying too hard to be mature.
All that's missing from that trailer was some edgy Linkin Park.
Or better still Evanescence.