The problem comes from "reasonable royalty". The price list should be set by the vendor and once set they shouldn't be able to change it depending on who wants to pay for it.
You can't ask one million or 1$ per unit from company XYZ and then turn around and ask a company that is your competitor ten times the price "just because".
I would add that no standards essential patent should ever be allowed to require a percentage of the final product price as a licensing fee. Your contribution to, say, a networking technology is not necessarily more valuable because someone else added a more expensive case, screen, or battery. It can hardly be "non-discriminatory" when the price is different for each product.