If I were selling something, I'd consider any form of payment in order to attract the most potential buyers.
But really nothing is easier and more convenient than PayPal whether buying or selling. Sure there are fees but those are offset by the cost of a stamp and envelope, the cost of alternative payment methods (MO or check), the effort and time spent going to the post office and bank, the convenience of having an easily-accessible online record of every transaction, and the protection/security.