oh black/dark brown and navy blue are classic colors which can suit many occassions. I think its not proven that black leather absorbs more heat than lighter colors, just feels warmer on the surface, is that right? I don't think your lady's black purse would get hot enough to melt that candy bar you stashed in there for your snacking pleasure
... if that's your concern
The reason why you don't see the darker colors as ladies like to color match their accessories to their outfits. During spring and summer they are less likely to wear darker colors and hence darker accessories like purses/hand bags... hope that helps!
Btw leather or leatherette ??