Chairs are probably the hardest thing to design.
To start, people are all different sizes and shapes so no one chair will be comfortable for everyone. Structural requirements can be severe, especially when minimizing materials for efficiency and weight reduction.
On top of that there are probably far more chairs than asses to put in them. Not that there is any shortage of asses ...
With this in mind I don't design furniture for mass production but rather for limited production: carefully detailed, expertly crafted and simply unavailable anywhere else.