I have to agree with Fatman, that the Satin fibers add quite a bit to action of the finished jig ; a major FUNCTION of the wool is to spread out these satin fibers so that they yield a more "3-D" minnow effect &catch water current more efficiently. I've been tying a thicker "bass swim jig" out of one of Hawnjigs special HU heads,where I tie a thicker wool body (the wool ,heaped up in front of a relatively small hook, also yields weedlessness!), then put in a LOT of white,blue ,and green satin fibers +flash material (blue/green sheer) to give a so-called "bass jig"(bluegill flavor!) look without the gum band (pittsburgh talk for rubber bands or silicone/rubber legs) appearance,which I always personally thought looked ridiculous! I tip the end with a SHAVED ,thin 3" rabbit fur strip-fantastic swimming action.
Still, regarding the wool fished plain, years ago famed angler &bass movie maker, Glen Lau, dressed his once famous "Lau Lure" with only a clump of plain dyed wool -his best DAY on the water was a catch on Lake Erie of 800 POUNDS of fish!!!!