That seems like something of an argument of perfection. Someone says something is bad, a critic responds that the alternative is not perfect. I'm a vegetarian so I'm against all of it really, but I find it hard to believe that slitting the throat and allowing the animal to bleed to death has not been improved upon. And animal welfare guidelines and laws backed me up on that. The only reason such laws and guidelines were backtracked from was because of the sizeable religious lobby.
The irony being that the halal manner of killing animals was designed to reduce the suffering of animals (with such prohibitions as the animals must not witness each other being slaughtered) but are now holding proper treatment back by turning it from a best-available practice at the time to a religious doctrine.
Seriously, look at the argument you just used: don't ban this bad thing because perfection is unobtainable. That's a flawed argument and you know it.