I think this is an extra credit activity. Its the last thing I want to do after cumming. But if I can get past the post orgasmic shut down I'm fired up again and ready to go again. It gets you points for the freakiness of the act. It is always brought up in horny conversation later as one of the hottest acts.
If you want to make love all night you cant be afraid to taste yourself.
I don't think it should be done all the time. Just to spice things up a notch