I actually read up on colours a lot on my own since I think it's interesting, and Cowrie pointed out something that I'm surprised more people don't know: Pink was originally considered a masculine colour, and blue a feminine colour. (Because pink is a diluted shade of red, which is the colour of things such as blood and carried a more masculine connotation.)
Not only were the colours different and carried different stereotypes, but even the actually clothing itself was different. In Victorian England, boys and girls alike would both wear dresses until they were around...five, I think. After that, they would wear shorts, and then eventually slacks.
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I wrote up a little thing on red a while back on why it's such a popular colour for lead characters, or characters in general. It's very thrown together, but has information which I found interesting on the colour:
"Depending on your sources, red reflects courage, passion, power, love, violence, strength, anger, death, danger, happiness, luck, excitement, etc. In Feng Shui, it reflects passion, love, and arousal, especially. In some countries it is the colour of marriage or of mourning. Also, in decorating, red inducing larger appetites, raise blood pressure, and induce shorter tempers, if I remember correctly.
With such a variety, you can easily find traits that are ideal for various characters, and not just in animanga, but all sorts of areas.
I'm foggier on this, but I'm pretty sure red has the longest wave length of the light spectrum, so it can be seen the easiest and travel the furthest. (Blue and purple are the shortest, which is part of why purple lights are so uncommon!) Red and green are some of the most common colours in colour blindness, however."
And this is how I spend my free time...studying colours and other generally irrelevant information. Colour stereotypes can be annoying, but like most stereotypes, will prevail and morph for at least a long while. It's actually quite interesting.
Personally, I prefer blue, because it's easier on my eyes and just more appealing, but I have no animosity towards pink.