Quoted from TheFamilyArcade:Insurance against what exactly?
Lets say you have a basically minty HUO game...with a cliffy (no damage underneath)...how much more valuable is it than a basically minty HUO game with a cliffy with some minor - or freak chip due to poor clearcoat or whatever - wear damage around the scoop being protected?
In each case the cliffy entire covers the damage. And, one would think, any additional damage is now impossible.
Is this going to have any real impact on the sale price?
Insurance against damage occurring. Sorry, thought it was obvious. I never mentioned anything about impacts to sale price. I guess it depends who is doing the buying and how picky they are. I have never bought a machine with Cliffys already in them so can't say from personal experience. However someone having them in tells me that they either really care about the quality of their machines, or are hiding some major damage. I would probably ask which was which and be guided from there.
To answer the OP's original question, as to why someone wouldn't buy cliffy protectors, for me it boils down to this:
1) Ramp protectors. Only a moron wouldn't buy ramp protectors. Replacing ramps are very expensive, and all it takes is one unlucky hit to crack/break the ramp. Buy them.
2) Scoop hole protectors, saucer, etc:
Get them. I see it as stopping damage from occurring in the first place. I get some people don't care if their playfield sustains damage, or don't like the look of the Cliffy. I am not one of them. Personal preference comes into play here obviously.
Mantis protectors are available for some machines. They solve the "look" problem and have less possibility of impacting playability, so are a great option for people with those concerns.