In a perfect world, yes. But often mods just see the reasoning from the original report and after they review it, they affirm because they agree. I remember that's what I have done in the past, though I did add explanations here and there.
Reports pile up yes, but there are enough mods where they can get everything done. I'm just not sure adding an appellate court system in there would help with the workload. Otherwise everyone would appeal and expect explanations and that just opens up a floodgate. However, I do think that this may be circumvented by asking for mods to give at least 50 character responses in their original reasoning.