Question

The laws of slaughter are not written in the Torah. They were passed down through some tradition via the sages. Given that, there seems to be room to ask what the reason is that they chose the current method of slaughter.
A common claim is that this is the most normal form of slaughter, or that the animal dies the fastest and does not suffer, etc., and that therefore this is the method we received. But today this is of course not the fastest form, not the most efficient, and not the least painful. In the United States they stun pigs with electrodes to the brain, and they do not understand at all where they are going, and they are cheerful and happy all the way to the facility, and die within a fraction of a second. 
If that really is the reason, and assuming there were sages who had the authority to change it, should changing the method of slaughter be considered? Or to put it differently: if we were receiving the laws of slaughter today, would they look completely different? (Maybe there would be disputes among the medieval authorities about the voltage and current intensity.)
Or is this in the category of a halakha given to Moses at Sinai, arbitrary and without a reason, and all the reasons people offer are just decorative?
(I know the Rabbi does not eat meat, and obviously the best method of not causing pain to animals is simply not to eat them, and if only we could merit a high level like the Rabbi’s.)