Algos provide liquidity and speed far more efficiently than any other category of traders. And, since they don't market time or trade swings, they can't contribute to bubbles.
Also, algorithmic traders are, by far, the least scummy people on Wall Street. They're in it for the money, they work hard, and generally don't care in the least about power. The real assholes are the ones who are robbing people of their companies, and those people have very little to do with arbitrage.