Clearly, they are strong enough for aid climbing, so there is one application. If you are climbing easier alpine routes where the chances of falling are minimal, but you are watching every ounce, then perhaps you would be willing to forego the extra margin of safety that a stronger nut would afford.
I don't know, it seems to me that nuts are your lightest protection to begin with, and that it would be the last place I'd try to save weight. The fact that I've never seen anyone carrying these nuts tells me they can't be very popular.
But you got 'em. My suggestion is to use standard nuts when the fall factor is high and save your ultralights for when you have more rope out.