The job of a common-law judge (which is roughly what we have) is far more difficult than that of a civil-law judge, since far more is left to judgment and the application of ambiguous precedent.
It seems the biggest problem is when people aren't bound by precedent. When do you overturn precedent? Plessy? Brown? Kelo?
It seems that many judges are not bound by precedent and many others simply pick the precedent that benefits them.
But please tell me what great intellectual powers it takes to memorize a bunch of court cases.