I know what you mean... But I love heated seats (when they work properly) and whilst it's only a few months or so of the year they get used, it's the principal of paying out, let's face it, a lot of money on a car that essentially SHOULD perform better in that department, it's not like it's new technology or anything.
To some it's trivial and silly, but to others we do expect better for the cost, they might as well have not bothered fitting heating elements in the seats, that's the point im making

I timed it at 15 minutes today - with a low heat starting to be felt, so would guess it would take around 30 minutes for the full heat to be in effect, no one can say that's acceptable surely!