Don't want the extra fees. Don't want the risk of having my Paypal account frozen or money being reversed from it due to fraud somewhere else down the line, etc. etc. Paypal 99% of the time sides with the buyer in a dispute, and that will leave the seller on the short end of the stick as far as the money and the item are concerned (if it's already been shipped out).
If someone wants to use their credit card then they can use Bidpay.com to pay me, and THEY can pay the extra fee, not I.