> That's what awnings (or solar overhangs, or light shelves) are for.

Right, this is my point. We already think about these things.

> Isn't the idea of mcmansions

I don't think McMansions, or whatever your favorite example of bad architecture is, shows that we've somehow lost knowledge. Architects and builders are aware of all of these things, but that doesn't mean there aren't still clients who want less energy-efficient designs for all sorts of reasons, like aesthetics.

We know how to build energy-efficient buildings that are appropriate for the location and seasons. We also know how to build buildings for other purposes, and are aware of the tradeoffs in how they use more energy. Energy conservation isn't the only goal in home design.