Why should we assign higher moral value the more they're intelligent? Aren't both capable of feeling pain?

I don't think anyone hunts cows for sustenance these days, and it's not like the majority of people needs to eat cows for sustenance. Society has just collectively decided that certain animals should suffer for our gain and that said suffering is okay. For me, that just causes too much cognitive dissonance.

Though, I realise that abstaining is easy for me on account of never having eaten meat in the first place; I've nothing to give up. I also don't particularly enjoy people preaching that someone should or shouldn't eat one way or another, because I grew up with that shit being preached at me and it made me want to pull certain people's eyes out.

I think it's healthy to examine societal biases and traditions, because there are plenty of things we do just because it's always been done one way or another, and breaking habits is tough, particularly on a societal scale. If someone comes to the conclusion that they're actually perfectly fine with eating meat and all of the impacts that has sits well with them, far be it for anyone to tell them otherwise.