I think part of the forbidding/inviting dichotomy is due to the relative widths of the buildings involved.

The apartment building is wide, and has but one entrance in that entire width. Entrances are sources of activity, and thus the apartment building has a long length in front of it where activity does not occur. Because the entrance is flanked by two such lengths, activity there is suppressed as well. In the case of the shops, however, the large number of entrances each generate activity that helps supplement that of the neighbouring entrances.

Furthermore, I feel that it is pleasing to be able to see the whole width of a building in a single glance. This make the building seem more manageable, and thus less formidable.

We exist on a horizontal plane: everything on that horizontal plane is supposedly accessible by walking, while things on planes above and below affect us only slightly. When we "look around", we turn our heads side to side, almost never up and down. When we can see all of the horizontal element of something (as with the narrow buildings), the impression is that there is less on the horizontal plane for us to deal with. To a certain extent, even if we do not take in the whole of the vertical element, we do not worry because the parts above are less accessible: we can look at them, but we can't immediately go to them.

In the opposite case, where we see only part of a horizontal expanse, the impression is that each plane in that building must be large an unmanageable. We can go to all of that horizontal expanse, but without some effort we cannot be aware of the whole of it at once. What we cannot see becomes a part that is nebulous and defined. And as it's supposed to be a part of the world that affects us directly, it becomes a little frightening.