Bring out the gimp
When the supplier has to provide additional tools, the customer needs to bring in a "frenzy" (my collective noun) of lawyers and a group of financial modellers just to understand the pricing model. What you end up with is a fundamental mistrust between the two.
And those with a clue that don't swallow the sales and marketing bullshit have a deep gnawing sensation that, somewhere, somehow, at sometime in the near future the whole three ring circus is going to bend them over a barrel all without the benefit of lube.