Because incentives easily misalign with imperfect information and because first past the post systems transform things into majority rule.
i.e. a judge's job is to interpret the law for a case, so you don't want to impair that with other incentives. i.e. the best judge is a program that, supplied the law and supplied the evidence, provides a judgment that most precisely approximates the law's intent in this situation. This can be very far from the people's present intent.
So if you give the people too much power over the judge, they will transform law-execution into present-intent-execution, something we do not desire.
If law were totally unambiguous and evidence were totally unambiguous, we might be fully constrained. An elected judge would still be unable to appease the crowd. But we know something: law is ambiguous and evidence is also ambiguous. We need the human here to disambiguate and match against statement and then intent. And adding political necessities to that process hurts it.
> they will transform law-execution into present-intent-execution, something we do not desire.
Are you assuming present-intent is clouded with short-termness?
In general, people want government officials (like judges, here government is in a large sense) to do what they, people, want. Maybe not immediately - though it's a complex questions, with assumptions and counterarguments, but not clearly leading to your conclusion.
We also see that modern state - where laws are complex and judges have leeway to interpret them how they present-intently want, has drawbacks. That's the problem which we face - and want to fix. How's your problems bigger than this one?
> We need the human here to disambiguate and match against statement and then intent. And adding political necessities to that process hurts it.
We somehow don't have mechanism to ensure the intent of a judge is as we expect it to be. Sometimes honestly - I can imagine e.g. a conservative judge who really never imagined a marriage for couple of the same gender (not a very good example, sorry).
i.e. a judge's job is to interpret the law for a case, so you don't want to impair that with other incentives. i.e. the best judge is a program that, supplied the law and supplied the evidence, provides a judgment that most precisely approximates the law's intent in this situation. This can be very far from the people's present intent.
So if you give the people too much power over the judge, they will transform law-execution into present-intent-execution, something we do not desire.
If law were totally unambiguous and evidence were totally unambiguous, we might be fully constrained. An elected judge would still be unable to appease the crowd. But we know something: law is ambiguous and evidence is also ambiguous. We need the human here to disambiguate and match against statement and then intent. And adding political necessities to that process hurts it.