Aside from Betelguezah's post. I understand everyone's position on this. and agree on difficult targeting. and yes i read developer letters, stating mob size increase was due to difficult targeting.

Though, it seems, the difficult targeting had mostly to do with rats, bugs, vermin kin.
Its possible then, the other mobs sizes could have stayed the same, while the "difficult to target" mobs, such as vermin kin only, would have a size increase.
editing topic then, reduce mobs to original size, minus "difficult to target mobs" such as vermin kin, or other mobs players had issues with.