Now, when you answered me, it will be much easier to make a decision for me! I think that:
1) Defense wall is an empty structure (box) made of cheap metal (so it can easily transported). So where should be rust, curvatures made while transporting, scratched off paint.
2) After emplacement wall should be filled with nano-reactive liquid that hardens on a heavy impact. Only most powerful weapon can break through and some liquid may be spilled (I think it has acid yellow color). Also box may be damaged while transporting and may not be totally sealed.
3) When it needs to move forward wall can be left behind (its pretty cheap). Liquid can be pumped out and used for another walls. In this case enemy can't use those liquid-less walls (unfortunately not in game).
4) Lamps may be only inside perimeter. And they are blue (used by military night operations). But I won't paint glow - its a daylight after all! (aaand I'm too lazy
Painted walls look nice and fit my back completely