For one it's a bit of a cultural standard - like appearing in a suit for the interview; it doesn't show your qualification, but it shows basic etiquette (it's no longer as usual as it used to be and not the best example, but I think it gets the point across). Also, an image helps you form a more personal connection to a person.

But I'm not a recruiter myself, so take that with a grain of salt.

I think that ‘personal connection’ is a easy way towards discrimination, just like ‘cultural fit’.

Humans are naturally more inclined to feel a connection to people who are in their same group.

Some societies believe it is acceptable to judge people based on their appearance. Arguably, most people do it instinctively. It is just that in America it was deemed illegal. I know there's an epidemic of plastic surgery taking place in some Asian cultures - people getting cosmetic surgery so that they can be employable.

Right or wrong, that is how some societies are functioning.

Sure, it is, and that's why you may not require one. But I can see why people would want that, even with no malicious intention, which was your question :)