1) I found sleeping in down pants and down jacket in my sleeping bag to not be very practical. There's no real way to ventilate if you're warm, and do you really want to fuss with putting on clothing in the middle of the night when the temperature starts dropping? Hell no, I'd rather just adjust my bag in my half-sleeping state. Good idea in theory, horrible idea in practice. Jackets work ok, since it's easier to ventilate your top, but I prefered to avoid the whole mess in the first place. I've tried it before, and it sucks.
2) In the evening, I sometimes draw my bag over my legs when staying up and enjoying the views. Snuggy in the backcountry though? No thanks. My sleeping bag will only be designed as a bag, ever. Again, good idea in theory, terrible in practice. Just too warm when you actually are awake and moving around, doing things, and when static, the bag over the legs works just fine.
3) If it's raining, you're in your shelter anyway, so I don't get the 'Wet' argument. A good book on tape on an iPod Shuffle works wonders during these times. Well worth the half ounce.
PS: take a dump in the morning and bring a pee bottle to bed (or use a floorless shelter, rollover and pee - my preferred method).