I like having a snorkle...
I also have a backfloat BC, that means it likes to keep me face down in swimming position.
Sure I can back swim too but its easier with me under the air bladder face down.
Pre dive, look around face down for interesting things to explore on the dive, while waiting for dive buddies to get situated and in the water.
I like to relax face down watching sealife waiting for everyone to get back on the boat at the end of a dive too, so relaxing.
Lets not forget water magnifies... Water also takes the gravity off a womans body... Bikinis and skin tight outfits... Hell Ya! Hey I'm a red blooded man, you put it out there... I'm going to appreciate it. You don't get to enjoy the view if your heads out of the water.
Life is so much nicer while your face is in the water. Why would you want to lift your head to breath...
Besides, if the wind is blowing you cannot be blown away from the boat as easly if your in the water with just the back of your head and snorkle exposed. Sitting up to breath or float means your catching more wind like a mast and sail. If the wind is blowing too hard you NEED to dive under the water to make headway...
Same is true with the currents to a certain extent. The more in the water you are the more stroke/power/effect you can get out of your kicks. The more headway you can make.
If your at the surface, wearing split fins, trying to rapidly flutter kick to the boat in a moderate current... Just sit back and start blowing up your rescue sausage!
Happy Diving.