I'm not an expert in the field of refrigeration so I'm speculating a bit, but I believe the won't work because the cause of inconsistency of temperature is that the insulation isn't as effective at every part of the cabinet (probably due to shape, what components are packed around the cabinet, etc.) so moving air over those areas would cause heat to enter the cabinet faster, requiring more cooling power. That might be effective, but I think the approach that's taken is more efficient, and that's what refrigerators are all about (They move like 2-3x more heat energy out of the cabinet that is put into the compressor, fans, etc.). The less movement of the air inside the more effective the insulation will be.
It's also worth noting that just insulating better isn't really an option (without developing better insulation) because refrigerators need to have as large as possible interior volume compared to exterior volume to be competitive, what can be fit inside is a definite selling point.
It's also worth noting that just insulating better isn't really an option (without developing better insulation) because refrigerators need to have as large as possible interior volume compared to exterior volume to be competitive, what can be fit inside is a definite selling point.