i think it has less to do with highlighting the pit than having her arm in the air as something to playfully hide behind - so raise your bare arm = showing your pit. why she couldn't we a top with sleeves - who knows. take a look at a "nightlife"/"where to go out" publication and you'll see lots of men doing the hide-behind-the-arm-pit shot. admittedly, they're mostly ads for gay dance clubs
let's agree to disagree about ladies shaving their arm pits. file it under my preference for
vive la difference. men are big hairy apes, women are smooth visions of beauty and grace. and before someone gets on my case, yes i realize it's a pain, and can be seen as oppressive, and why don't you go shave yourself mister, etc.
a while back i was thinking of starting a thread on personal grooming/trimming habits. maybe we can re-purpose this one...