Fronts do indeed wear more than rears, but no matter as the fronts wear much rounder because of the weight on them. The extra rubber you have on the rear because of less wear is a misconception since the rears ALWAYS tend to wear out of round, leave them on without rotation and see if you can get them to wear down to wear marker, 9 out of 10 times they won't. You'll end up yanking tire for shaking and noise with what still looks like plenty of tread on them. Been there several times, you can jack up wheel and whirl it to see the obvious out of round condition. Rotate that to front and you can pick up on it far easier than a front worn same amount of time even if front worn way more. And then your round front tires that you just put on back are now going out of round.........why I don't rotate at all on FWD. I'd rather have the little bit of noise in back to tell me how tire wear is going back there.
I don't live where there's lots of ice, but when I get it I simply slow down. Virtually no rear end sliding around then. In the rain the front tires will hydroplane even with lots of tread left on them, that can be severe and absolutely silly to me to have new tires on back then, up front they stop the hydroplaning way before you are back end sliding. If back sliding in rain then again I suggest you slow down. I don't drive like an old woman and seem to have no trouble at all.
It appears to me all the suggestion of new tires on back are in response to legal issues (incorrect and often not caught up with the rest of the world) and people who seem to be driving too fast for conditions so as to lose control of rear end. Granted, simple straight line panic stops can test tire performance but driving competence/incompetence or ABS will far outweigh whether the new tires are on the rear or not. Having ABS actually makes up for not having new tires on rear. Add to that the fact that at stop the weight transfers to the front and it should be obvious the new tire not going to help much if it does not have maximum traction to work right.
To me you are giving away a massive long term amount of guaranteed much surer directional control along with steering performance, driver comfort and ease at the wheel, and stability over the long run for a second or two of what you HOPE is better at panic time. Modification of personal driving habits will reward you far more than new tires on the rear ever will.