I know many are using paypal to cash out after receiving, but think of it this way. If you have bitcoins, say you received them for a service, and you use them to buy goods from someone else, there is 0% transaction fee to use bitcoins. Better than pecunix, paypal, or traditional credit cards.
There is a small transaction fee for using bitcoins. Not everybody is getting charged that fee at the moment, but it is something that is happening even now. Those transaction fees go to the node operators for "large" transaction that take a bit more processing for whatever reason in the network. I don't know all of the details, but it is something built into the network.
Regardless, it certainly is a much smaller transaction fee than the other payment methods, and a heck of a lot less than credit or debit cards. With the fees that merchants pay for credit card sales, I actually go out of my way to make sure I pay cash for purchases at a small Mom & Pop store in my town explicitly so they can end up keeping more of the money I'm giving to them (pulling it out of an ATM where possible prior to the purchase). Large box stores I really don't care about, as they already have "special" arrangements with banks for these fees anyway. If I am without cash and using plastic anyway, I also try to explicitly request "POS debit" instead of "credit" even if the store clerk is clueless about the issue for the same reason... it makes a difference in terms of profits to the store.