Great fun, but impracticable ...
Many regions of the world are wood-adverse.
Take the Asian Longhorned Beetle is a large wood-boring insect native to China, it will chow down on any wood remotely soft. Now, thanks to softwood pallets there are large colonies in the USA, Canada, Europe and elsewhere.
The only answer to these pests are hard-wood or concrete.
Then there is the bureaucracy. They are the architects friends who seem to have but a single purpose in life - to generate business for architects. Then there is the construction trade who think everything but everything is beyond the intending home building plebs. Seemingly only the building trade can employ unskilled labour and produce a building.
Unfortunately, these designs in wood are impracticable for my part of the world, well entrenched as it is with Asian Longhorned Beetle, so we create in concrete. I have constructed three buildings, now, one being my home and the other two what government calls 'mini-hotels' (which have over thirty rooms each.
Being a pleb builder, I studied very hard. I did unusual things such as making all 'techno-structure' (pipes, wires, etc) accessible with the minimal of bashing concrete - unlike professional builders who bury all such infrastructure under mounds of concrete. I used insulating concrete forms (ICFs), factory made rebar forms, welded window inserts into which windows (or doors) can fit knowing the frame is dead square.
Even crazier, according to the local 'construction experts' was my use of large-diameter plastic pipes as concrete forms instead of using tatty-looking things made from wood and nails. I simply split piping longitudinally and used packing bands to hold them together whilst the concrete dried. Strangely several 'professional;' builders are now copying my technique in the area.
My first mini-hotel used containers (surplus or 'hot' units costing me USD$300-400 delivered) and it took an engineer to explain to the planners that a container will support many, many times their weight and that my height of five-seven containers wasn't a challenge.
I wish Wikihouse every success, however I fear they will best succeed in places such as Africa for 'advanced' countries throw up to many obstacles to make this practical. I must admit, there are many authorities in Canada, outside the larger cities, who will happily accept DIY home plans, and offer technical help in making the plans meet 'code'.