Don, you're correct. As I've indicated, the original recipe does call for a palmered hackle, but it calls for the rubber legs as well.
There are only two fly types I tie with rubber legs- topwater as you've indicated, and bottom flies like these. Why rubber legs on bottom flies? The action on liftoff and return to the bottom is hard to beat. It drives the smallies nuts. I usually use this type of fly in a clear water sight fishing situation where I can read the fish's response.
I have no real experience in trying to incorporate them into streamers or wet flies per se, so I can't speak to their effectiveness in those types.
But now you've got me thinking.....