This is what dynamic cloth is for. ;-)

Body handles are easy to apply to conforming skirts etc. because they can be grouped to one actor i.e. the hip) without losing more functionality than a conforming skirt does anyway. In other words, it's making the best of a bad job...

However body handles for an opening jacket, for example, would often have to influence more than one of the "basic" actors of the clothing: chest and one collar, most probably. Maybe it could be done with ERC, but I figure life is too short when the cloth room is a click away.

In your other example of clothing that can be slid down the figure, the problem here is that it needs to stop being conforming at some point. A pair of pants which started off conforming the the figure's hip would not work very well when they were positioned around their knees. Again, some would say that clothing that falls off is the natural M.O. of the cloth room anyway. But not me. ;)