I work at a sex shop and I've noticed that most women buy 8-12 inch dildos. I thought women were alright with 6 inch dildos. Also, they always buy black dildos. So, do women secretly want big black penises?
I don't even own one, but with dildos and toys like that, the more extra you have to hold onto, the better control you can have with it. You need a bit to grip onto. It doesn't mean those girls are shoving the entire thing in there. And even if they were, that only represents the women YOU see who buy toys, lol, not the whole female population. Color is irrelevant. They also have neon ones and every color of the rainbow, and we'll never find a man with a penis any of THOSE colors, so it really makes no difference.
maybe they like the black dildo's because it matches their dress, purse or lingerie. It could also be because they like to do it with the lights off and like to pretend they are having sex with an invisible man because they don't see the black dildo in the dark.
Because it's better to have a bit extra, especially with dildos. They can stick as much in as they want, and leave the rest out. With a penis on the other hand, it's pretty much always completely in, which is where size can be a problem.