The REASON you can't have it both ways are already stated. You want BOTH the damage and healing boosted more. You keep using an extreme example of Von's Monster with a bunch of boosts. What about a simple vampire with colossal? Are you telling me that has no effect? The simple fact of the matter is that it's 100% fair the way it is and they aren't going to change it just to make death over powered.
I guess that a weaker drain might be affected by this. It's just annoying because it only affects Death. @Oran: Have fun trapping for that, enjoy wasting an extra 3 rounds for four feints, and dying if you don't bring other heals.