I think the "kits" you're looking for are the laser-cut wooden ones and then there's always scratchbuilding. It would be EXTREMELY expensivefor the mfg. to re-tool their process, just so that the detail parts aren't pre-molded on the walls.... those details might even (through testing) have proven (the the mfg.) that they add enough strength/thickness to the plastic so that it doesn't warp too bad in transit....
I always thought of three levels of kit building:
1. (simplest) - pre-colored/most everything molded on - you just need to glue a couple of walls and the roof together. It might even snap together. Roundhouse kits, and the simpler structure kits come to mind.
2. (moderate) - the kits that come as a bundle of parts (more than the 3-5 of a simpler kit) and a blown up diagram of where things fit. Steam loco kits, and laser-cut wooden kits come to mind.
3. (hard) - an idea, maybe a blown up diagram from a previously finished kit that can't be bought anymore. In short - scratchbuilding.
-Dan
Builder of Bowser steam! Railimages Site
I wish the manufacturers of plastic structure kits would quit molding detail on the walls of their structures that need to be painted differently than the base color of the piece. For example, the window sills, ledges and cornices of brick structures, which are generally concrete or stone, need to be painted a contrasting color. In the case of my most recent effort, the Walthers Geo. Roberts Printing Company, there are brick fields between the concrete post and beams. I had the choice of spraying the walls the brick color and brush painting the concrete or spraying them a concrete color and brush painting the brick. I chose the latter. Brush painting the detail is tedious, time consuming, and probably my least favorite part of this hobby. Since the detail is almost always a contrasting color to the base, it usually requires two coats so the base color doesn't bleed through. No matter how careful I am, there are inevitably goofs which require touch up painting to the base color of the piece. I am sure I spend as much time doing the detail painting as I do on the rest of the kit building combined (base painting, brick mortaring, assembly, and weathering and decaling). How much easier it would be to produce different colored parts of the walls as separate pieces that could be spray painted and then attached to the wall. I am sure I could glue these parts to the walls much faster than I could paint them and the finished product would be much better since there would be a much sharper line between the parts.
I know this would add some cost to the kit but it is a price I would gladly pay. When I think of the additional time detail painting adds to structure assembly, it is not hard to figure out that the additional cost would be well worth the time saved. Besides, it would be beneficial to the companies since the faster we can build kits, the fast we would buy them.
Some might argue that built-up kits are an option. The choices in built-ups is extremely limited. Also, with most built up kits, the color is molded into the plastic rather than painted. Unpainted plastic looks like plastic. You can weather it with chalks but it still won't look as good as a painted and weathered structure.