Scrappers are pure damage beasts. especially when it comes to focus on a single target aka scrapper lock,. a brute needs to have as much agro as possible to max out fury where they can indeed do impressive damage. but Scrappers can with their crit hit mechanic out pace nearly any class outside of a blaster, and blasters can match that with easy aoes.
Brutes do however get a serious increase in resistances over scrappers so they have the ability most often to survive the initial retaliation a bit better then scrappers.