Specialist computer furniture is tailor made for people whom, for whatever reason, cannot operate a computer under normal conditions or without suffering from pain.
This can apply to children who need a lower desk and chair to suit their small stature, or wheel-chair bound people who need to have a higher desk in order to position themselves closer to the PC.
You can also get specialist furniture such as child-proof desks, which contain lockable compartments for protection and security.
Comfort is a hugely important factor for computer users, especially to prevent repetitive strain injuries. Standard chairs and desks are not always suitable for some computer users, hence the existence of specialist furniture.