Oversight, Ignorance, Compromise, or Dumb?

Walking the dog today, I passed a house that got me thinkin'.

No camera with me, so I'll have to describe it.
The front of the house faces south. It's a two-level with a garage on one side. The first floor looks pretty normal: front door, windows... But the second floor facing south is all roof. A steep roof-line runs from the top of the first floor all the way to the top. No windows or anything. It's not just a giant attic, though, as there appear to be windows at the back of the house.

Why would someone design their house like this?
It's not a particularly busy street. It's in a rural area, on a large lot, well away from the road.
Why not have a few windows on the south side? Living in the northern hemisphere, southern exposure is usually a key location benefit for real estate properties.

I can only think of four reasons someone would choose this design:
1. Oversight. Very unacceptable for professional designers and builders, but excusable for a homeowner who lacks experience. This seems like a fairly major thing to overlook, though. So, perhaps it's better described as:
2. Ignorance. Same description, bigger scale.
3. Compromise. Hopefully this is the most likely explanation. Every window that's installed, every angle that's cut, etc. has a cost attached. Maybe the budget didn't allow for this side of the house to look good. Maybe the owners preferred putting their efforts elsewhere. Maybe they recognized that this design direction wasn't perfect, but gave them the best results for their priorities (for example, if they like lots of un-broken wall space but couldn't make the rooms larger).
or
4. Dumb. Some choices are just unexplainable. Maybe you could call it "personal taste", but this particular case seems as much about utility as tastes.

I wonder if I could apply the same four reasons to other baffling decisions that I see made around me.