Do you know why baboons have pink/red bums? It's to show the male that they are sexually ready.
Now for the lipstick. Pink or red lipstick is attractive to most men on a subconscious level because it symbolises a woman's aroused red or pink labia. This could be why you like it.
Women choose the color based on what they feel suits them and their activities. I wear pink because it seems more natural than any other color. I don't go for the intense pinks though, just the subtle ones.
Fashion also plays a big part of color choice. The colors go in and out of fashion just like clothes do. So if everyone is wearing pink then it's most likely because it's 'in'.
I don't know maybe because pink is the color for girls.. and sometimes pink is the closest color to our natural lip color and also there are many shades of pink so they have more choice.. but I don't know and I like using red instead of pink..