Yes, I would. If an animal needs to be killed, this is one of the most humane way to do this. Where I'm from, a lot of farm animals die more painful deaths (nobody can afford electric shockers there).
This is one of the least painful ways to die. If I had to die and wanted a painless death, I'd choose being stunned with electricity and not feeling anything.
> above is obviously very cruel
Argument "it's obvious" works when something is obvious to the person you're talking to. In this case, it's obvious only to you.
And if "it's obvious" is your best argument, it usually means you don't understand very well why you came to that conclusion. Think about it.
> cruelty of the above is only ignored because it's normalised through culture and tradition
Yes, and it's not normal to you because of your culture and tradition. People's views are formed by culture and tradition, yes, there's no discovery here. If you grew up on a farm and saw animals getting slaughtered since your childhood, this idea wouldn't be so shocking to you.