That was throwing a bunch of random tech at the wall to see what sticks. But I'll play devil's advocate as best I can.

PEX has been around long enough to be allowed by code. Something I will now make up on the spot, which may or may not be better or worse than any existing plumbing technology, is not: BAM ceramic, wrapped in nylon fiber and epoxy. I don't know anything about how this material would perform as plumbing, and neither does anyone else. I only suspect that it would be practically immune to clogs. How would I know how it might actually perform in real-world conditions? No one would be allowed to live in the house I plumbed it with.

Gypsum wallboard might be topped by plastic or paper panels filled with phase-change materials, to help regulate the temperature of interior rooms. Some phase change materials are only about 4-7 times as expensive as crude gypsum. Sodium chloride sodium sulfate decahydrate sandwiched between HDPE sheets seems likely.

You can now buy 120V AC 60Hz outlets that have built in USB-A 5V DC charging ports. Some off-grid solar-powered homes have refrigerators that use 48V DC. I know my own home is filled with AC-DC or AC-AC transformers, most of them are not very efficient, and few follow any kind of standard for their connectors. 48V is the typical voltage used for Power-over-Ethernet. The advantage is that you can use one expensive and efficient power supply to power all the electronics devices in your house instead of 50 cheap and wasteful wall warts.

We couldn't upgrade US domestic voltage because we'd have to replace practically every 120V circuit breaker out there that is only rated for 120V on any given path to ground.

Some municipalities require a sewer connection for any building to be fit for occupancy. Some specifically regulate the disposal of human waste. Those regulations usually predate modern composting toilets. I have read news articles where eco-hippies are threatened with eviction from their own home when they ask to have their muni water and sewer shut off because they're going off grid for the benefit of mother Earth, or something. Not my thing, but some people are into it.

Fiber optic lighting can use high efficiency sulfur plasma lamps or direct solar to light interior space. The Smithsonian Museum uses it in some buildings, for a variety of reasons that don't include low cost. Direct solar fiber lighting avoids solar power conversion efficiency and heat or color rendering issues at the endpoint. Embedding optical fibers in concrete can produce translucent concrete, which has potential lighting applications, such as light-emitting countertops. The idea might actually be from the 80s; I'm not aware why it never really caught on except as a footnote on "whatever happened to the technology of the future?" type of shows that sometimes appear on the lesser-viewed niche television channels.

Steel also has a notable advantage over the wood studs available in 2016. You can get steel studs of consistent quality, and all of them are rolled straight and cut square. But it took an overly long time for them to make it into the building codes, and the codes for steel-stud construction are an order of magnitude more complex than for wood 2x4s, simple due to the greater number of options available to the builder. Steel studs have gauge thicknesses, shape, nominal dimensions, alloy compositions, anti-corrosion coatings, etc., whereas wooden 2x4s or 2x6s basically have a (mostly) integer lumber grade and decades of institutional builder knowledge behind them.

Can you imagine what the building industry would look like if builders adopted new structural members as readily as software pros switched languages and frameworks? Every house would be dirt cheap and look unimaginably awesome... and would unexpectedly kill 0.05% of occupants for no readily discernible reason. Builders don't need to go that far. They could adopt new tech more readily without worrying about killing anyone.