Imagine that from a development standpoint, 80 percent of the gorgeous buildings we see in TW media being given detailed interiors; remember, TW won't have empty rooms for interiors like PR. Peek into houses in screenshots and videos, and you can see the sheer amount of detail that goes into interiors in TW.
While you make a good point, I'm happy we have even 35 percent. Plus, if you enter a firefight without an enterable building next to you, I'm sure the mappers have integrated alleys, fences, walls,
et cetera to make up for it.
See
Traction Wars - WWII Realism Game - Dev Blog #21: Digging into the Detail (Part 3/3) for a glimpse of the amount of detail that goes into placing objects for a single non-enterable house.