However, given that we live in the real world filled with lazy/busy clients. Or in my case - I often know more about what the clients are trying to sell than they do .. I end up writing a lot of the copy.
I charge for this service, and let them know ahead of time. Given how often this creeps up, Ive learned to expect this with certain types of clients and build that into the pricing I quote them. A lot of people consider writing text copy to be work ( it is ) and thus, don't mind handing it off the an experienced writer.