(1) As the others have said, use the fee-regular-business PayPal to get your Seller's and Buyer's Protection (you get refunded if you don't get the goods).

(2) Another reason is that fee-regular-business PayPal payments make it easy to produce a Paypal address-postage shipping label -- just a simple click, and then you add a few simple things like the class of postage and the weight. (You can also produce a PayPal shipping label for anything [like after paid as a gift/friend], but you have to go through all the trouble of typing in the address and inserting the email address of the recipient. I also don't like doing that because it is against PayPal's policy, and they might object if you are always sending things [via PayPal shipping labels] after a friend's gift. By the way, here is where you go to produce a PayPal shipping-postage label for any non-eBay, non-business, any transaction:
https://www.paypal.com/shiplabel/create/ )

(3) the printed PayPal address-postage labels are also good because they give you a discount on the postage and have free tracking.

Robert