Why are Houses "Different" to Any Other Product?

I happened to recently see and article on Interest.co.nz about surviving a house renovation. I've written on this before under the "Building as a Mental Health Hazard", but more keeps coming to me.

My background is in manufacturing operations and product design, and the problem we had with separating design and build is that the designers become divorced from production realities and things get less practical, and therefore more expensive, to make.

The best place I worked for put new hire design engineers down on the production lines as techs for three months: no exceptions - including more than one PhD. Some of them didn't make it as their practical skills weren't up to snuff, but those who did were much better product engineers for it, as what they designed was practical to make.

I can't help but wonder if that's the case in the building industry; where if designers don't know the builder they're working with, and vice versa, it creates a gulf of knowing what the other is capable of, and from that come problems.

My own preference would be for a designer who has spent time on the tools as a builder, using modern construction techniques like prefabrication and materials like SIPS - but still has a strong aesthetic of simplicity and colour sense. Something of a unicorn, I suspect, as finding someone who can design something where the simplicity is convincing seems hard.

In product design terms, features and styling keep being added to obscure that the fundamental design is unimaginative and the functionality is "acceptable". 

Modern motor vehicles are good example. Manufacturers keep making car cosmetics ever-more complex and endless gadgets keep being added to very staid underpinnings that, while fine, are typically very dull, while the complexity works against reliability.

As an instructive (for me) example from building: I watched a friend get a design from an Architect, who had worked in government for some years and was a long way from building reality. The original design was very complex: it had 11 level changes in the floor slab alone. Admittedly a hill site, but still! The architect also had a distressing habit of body-scaling things like ceiling height to himself (5'8") when my friend is 6'3". In the end the ceilings went up, hallways got wider and the number of level changes came down to 5 or 6 (from memory). And the builder stopped having attacks of the vapours.