I think you have got in in a nutshell there , Tom, which is why I was getting frustrated with what was being said.
I have nothing against rusted metal effect, and with some work(which is available because you are not having to assemble numerous parts) you can smooth down the grains.
Interestingly I have noticed more minimum gauge layouts at exhibitions and mainstream magazines do cover the subject. Number of active members on this forum is down, for a variety of reasons I won't go into.
For what laser cut wood can do, have a look at these 4mm scale building kits.
Yes there is a lot of development work, but I assumed that once you had it designed it on computer, it could be cut as and when required, as is done with 3D printing.
Interesting to compare the costs of 3D printing and laser cut wood. The wood kits above look incredibly good value, which suggests the material is not expensive and the process is also cheap, but 3D printing still has quite high production costs, and apart from time, relatively low development costs.
Traditional resin and metal casting have the additional expense of materials used to make moulds etc, and are not necessarily produced to demand, but in advance.Injection moulded plastic is in a totally different league for development costs which is why it is only sustainable for high demand items.