Because Stripey wants her hair brushed too, and she has figured out which drawer is the "brush drawer". As soon as I open it, she is reaching down in it to grab a brush (any brush). And if I do my hair first, she fusses and tries to climb on me. So I have to brush her first, and she is willing to be brushed for as long as I am willing to do it. (My arm got tired after 15 minutes one day). She also just sits on the counter, waiting.
I should put my own brush in the bedroom somewhere.