How many buyers do you think actually walk away from cars due to shoddy cupholders? I think the amount of complaining indicates that most people go on to buy cars and then complain.

What this says to me is that the automakers have a cheap gimme to improve customer's reactions to their car, and they essentially leave money on the table when they don't take it. Cup holders are not ABS brakes or cruise control or a great sound system even, but neither are they nearly as expensive as any of these. Even the apple iPhone is (subjectively to a phone engineer) 90% the same as its predecessor, they just fixed the 10% that brought them from good to great.