Why recently manga and doujin draw more of that 'position'? Is it good? Should I try it with my GF? @///@
They draw it because it's very visual, in the same way het sex is. The extreme pleasure effect is fictional though, as far as I know.
My suspicion is that it originated among otherwise straight authors doing girl-girl scenes without really knowing much about lesbian sex (how else would girls have sex?), and it spread from there. Now it's almost mandatory as a "finishing move" when it really isn't in real life.