Pixel consistant textures

The pixels in many of the old mobs aren't very consistent with the most of the creatures in minecraft.

The bat for example has much higher definition pixels than the pig while the ghast has much lower definition.

Their size difference would be understandable if it weren't for: Newer mobs with vastly different sizes having pixel texture consistency. For example; the ravager and the parrot, have a consistant texture with the pig despite a very large difference in size while still having them be high quality good looking textures.