A couple ideas:
* Reclaimed Materials - How can you build both with reclaimed materials, but also materials that future generations can reclaim for themselves? For example, a timber framed barn could use natural/local/reclaimed materials, but it would also be interesting to see how you could re-reclaim those materials (ex: in 2100, they can use the wood from your build, which you reclaimed from a barn built in the year 1900. 2x4's won't do that.
* Build Over Time - In addition, you could either build a giant house today or you could build what you need now, anticipating the need to add on over time for stuff like family expansions, home businesses, etc. I could design a 4,000 ft^2 house that would serve my needs and probably my future needs, but there would be a lot of wasted space. Or, I could design a 1,000 ft^2 house and have in mind where I could expand/retrofit over time if I chose to have kids, wanted a workshop/craft room, etc. Also good if you want to minimize your mortgage by spending money as you earn it rather than as someone is willing to lend you.
* Efficient Space Design - If you are paying for space, you want it to be useful. Especially if you want to save money or pay a premium for higher quality finishes, you want to consider what you really need/want.
You don't want to pay to heat or cool space that doesn't make your life any better. Hallways are not usable space. You could make it better by adding built-ins or some type of storage. In addition, my hot take is that walk-in closets are overrated. In my childhood home, my parents' closets could have been another decent-sized bedroom. I think it would be better to have built-ins that span the length of your bedroom and have a chest of drawers as a nightstand. If you can't fit all your clothes in a reasonably-sized wardrobe, it's time to make a goodwill pile.
* Proposed Rules of Thumb - "Does having this raise my quality of life enough to justify the expenses, both financial and environmental."
I'm a little biased because I love midcentury design, but I picture Frank Lloyd Wright's Usonian Architecture. The emphasis on larger outdoor/community space and smaller bedrooms. Architects should make a point to incorporate some natural materials and build a house that pays tribute to its site (ex: adobe, local stones, and desert colors in the Southwest).
3D Tour of Taliesin West:
https://franklloydwright.org/3dlab/