"where you want to slow down and not risk a front wheel skid."

the front brake still has more stopping power on a descent. while its true that a newbie might over modulate, once you get the hang of using your front brake you should rely on your rear brake largely for emergency situatations. this is coming from someone who has ridden down 500-600 foot descents at 30-40 mph for 300ish days a year for decades (lived on capitol hill seattle and now work on pill hill in pdx).