why is every male lead the black hair, black eyes stoic cold guy with a soft heart underne...

There are fluffy silver haired ml, a blond ones too (≧∀≦)

Let’s not forget the red heads and rare occasion when there hair is brown.

black hair is superior, especially with red eyes

Yes the favored traits

bruh that's so true, it's rare to see one with brown hair

appearances vary, yes, but what I'm really getting at is that they always have the same personality

I’m here waiting for a manhwa with a ML that has gradient or multi-colored hair like aaa black with streaks of white would be so cool (≧∀≦) or even someone who can pull off half-half like some todoroki haha

Long haired green ones too~

Some mls are like puppies, and yandere so it varies drpending on the said traits
Black hair + red eyes, stoic and cold (knight or a duke)
Blonde + blue eyes, most of the time princely? Lol, (prince or a ruler)
Red hair = energetic, hot headed (mistly knights)
Brown = friendly, boy next door or childhood friend (rich merchant type or childhiod friend)
White / bluish = holy? Lol church affiliated (paladins or priests of some sort)

Agree with what you said, but ML with aloof personality (emotionally distant) makes the stories much more interesting.

Personally i like the puppy dog type