Simply put, North Americans prefer sedans over hatchbacks.
I like hatchbacks, and the Golf over the Jetta. My entire family hates hatchbacks and thinks they're ugly.
N.Americans expect a wagon to cost the same or close as its sedan sibling. When BMW priced the 3 series wagon higher than the X3 SUV, guess what 99% bought...
The 3-series wagon is barely more than the sedan, and that has always been the case. For '17 the difference is $1500 and that includes a pano sunroof and power tailgate. So it's a good value in comparison to the sedan.