> the percentage of people who responded positively was significantly higher than the percentage of people who ultimately chose to pay for the option in actual sales

I'm guessing it's (at least partially) because they weren't offered a'la carte, but instead bundled with the "premium" interior package only offered in the most expensive trim.

This bundling is the only way I've ever gotten the option of heated/chilled cupholders (which are awesome, by the way).