Yeah, because giving it 200+ penetration is really going to affect balance when the best armoured vehicle around at the eighth minute mark is a Stuart. It already penetrates everything at the eighth minute mark.
The Jagdpanzer IV can already reliably penetrate mediums, so - again - this change would only affect its performance against heavies.
Also, @ people saying the Jagdpanzer is the best TD in the game. It is. But it had better be when it costs as much as two StuGs, which have a much greater damage output and are better against infantry.
the jpz4 is going to curbstomp every allies armor in the game if it get a penetration buff. It doesn't matter if it's more "consistent". It's just going to "consistently" kill allied armor, light, medium, or heavy.