I'm not entirely sure on the situation in US jurisprudence, but up here verdicts can be tossed out if the defendant had inadequate representation at trial. So there's a strong incentive for the legal system to ensure that everyone, even the most obviously guilty offenders, has a good lawyer.
But the lawyers still get shit for it; go look at Marie Henein defending Jian Ghomeshi.
But I'd rather someone get a rock-solid 15 years in prison than a 25-year sentence that could well be voided on appeal simply because they didn't have a good lawyer.