I don't totally disagree there, but the fact that GM/Buick decided to line up the trim levels with the Subaru Outback XT (and put the plastic cladding on it, too) means they had a key demographic in mind that's a bit different than most wagon buyers.
On the pricey end, you get the Mercedes E-class wagon, the Volvo V90, then V60, the BMW 3-series wagon, and Audi Allroad which all still exist. The VW Sportwagen and Alltrack are being discontinued. If you look at brand research, the buyers of the wagons often have the highest household income of brand customers.
I personally think Buick was a bit foolish to line it up against the Outback XT - they should have lined it up as a more reasonably priced alternative to the Luxury brand wagons. Less focus on the sporty/outdoorsy, and more on the practical comfort. As such, it seems like a mistake to make leather available on the Essence trim only.