In a completely different housing market (Italy) a lot of the hype is - besides "luxury" - on energy efficient/energy saving housing.
But the reasons (from the constructor/realtor viewpoint) are easy to understand, once the "basic" building costs are considered (and they are not-so-different between a "poor" home and a "luxury" one) the rest is "accessories", and there is a larger margin on these than on the "basic" construction, in the sense that the increase in the selling price as a "luxury" home is much larger than the added cost for these accessories, and this without considering the "fake only luxury" cheap ones sometimes used.
But the reasons (from the constructor/realtor viewpoint) are easy to understand, once the "basic" building costs are considered (and they are not-so-different between a "poor" home and a "luxury" one) the rest is "accessories", and there is a larger margin on these than on the "basic" construction, in the sense that the increase in the selling price as a "luxury" home is much larger than the added cost for these accessories, and this without considering the "fake only luxury" cheap ones sometimes used.