We have island scene patches...
...grey patches...
...multi-colored patches...
... carbon fiber patches...
... clear patches...
... and graphite patches!
Why? Because that is what is cool this year. If you don't have a board with tail patches throw it away NOW, because it won't work right anymore.
Actually, tail patches add strength to a weak spot in the tail between the foward and rear fins and change how the tail flexes. They have been around just as long as the carbon strip stringers of the 80's, but suddenly every company is jumping on the bandwagon.