Values points ≠ Sells points.
Imagine this sales pitch...
Buy our points for .035 and we will give you .015 cents in value towards redemption on flights.
Why would anyone purchase points when the redemption value is less then the cost of the points?
The current model is vague and ambiguous, thereby allowing United to sell points at a disadvantageous rate. Imagine how it would look if they suddenly change the sales price to purchase points in order to assign a lesser value to the points we've already earned.