It occurs to me that wounds on high level characters suffer the same problem as traffic fees to rich people... They just don't do enough damage to make it matter.
My suggestion is that rather than taking a flat number of points from a stat, that all wounds instead inflict a percentage of stat damage. This will help them remain meaningful even to high statted characters (who will now suffer penalties in the, potentially, hundreds of points) rather than simply a minor inconvenience in the form of a few measly points. This could also be represented by a penalty that increases based on the size and severity of the wound in the event that wounds build upon one another.
Wounds are great, and I love them as a mechanic, and am very interested in seeing disease and such implemented using a similar system but if I understand how they work correctly, then we need to see some buffing of wounds penalties to make them truly meaningful at every level of play.