A lot of people are saying sand shortage, but surely weight savings matter more? If your building is 6x lighter your foundations can presumably be a lot cheaper?
In that case, you should be comparing engineered wood with concrete that includes basalt fiber composite rebar [0] and weight-cutting aggregates like expanded polystyrene beads [1] and loose (basalt|carbon|glass) fiber. In small-building construction, a no-steel concrete wall could be just 2 inches thick where steel-concrete building code might mandate minimum 8 inches just to prevent swelling rebar from destroying the wall from the inside. Also, basalt rebar is trivially bendable, so curved shells can add strength from geometry where straight steel rebar would be limited to using rollers to bend every bar to the correct curvature or to use doubly ruled surfaces like one-sheet hyperboloids and hyperbolic parabolas. And more non-sand aggregate means sand shortage has less impact, right?
There are a lot of ways to save weight on buildings, but not all of them translate well to building codes that can be used by building contractors without having a staff engineer on site to determine whether the equations work out to acceptable structural strength or not. And all the building codes out there for wood are going to be for standard dimension lumber, and not specific types of engineered wood. Until the codes are updated, the building inspector will look at your cross-laminated composite wood beams, look them up in his book, and tell you that your plans don't conform to code.
Not to mention that once your houses are light enough to blow away in a strong wind, now you need to anchor them to the ground with cables and hooks, and wind forces and the stresses at the anchor points become a whole new engineering problem.
Cities aren't going to be made of "wood". They'll have to be made of ANSI/ISO-standard-X-conformant structural members and ANSI/ISO-standard-Y-conformant processes. We'll get there. Slowly.
