The desire to shift from materials that have high cost in terms of eg petro-contribution or high energy production (aluminium requires intense energy; marble requires a movement of the earth).
The problem for many sceptics is that the alternatives aren’t as durable. Timber rots, reeds wither. This is why the demonstrator projects ar often temporary projects: exhibitions and installations.
But only a problem if durability is important.
Not a problem if materials can be easily replaced.
But a problem if durability is what the architect is after – the monument.
The most difficult paradigm shift is perhaps that in the mind of the architect – that it won’t be there forever.