The big advantages are:
No risk of chargebacks this is especially important for international transactions, "at risk" merchants, high value low margin transactions and escrow services.
No need to qualify for a merchant account.
No need for the purchaser / sender to have good credit. This by the way is a big market.
No risk of identity theft. Credit cards were never designed for transactions over the Internet and their use over the Internet is inherently insecure. They were designed in the 1950's and 1960's for in person / card present transactions. All the industry has managed to do is lessen the risk. Furthermore services such as PayPal are hamstrung by using credit cards as a funding source.
Very low or minimal transaction costs.
Here is my favorite: Bitcoin is the only electronic payment method that can be used to give alms to the poor directly. How many homeless persons have merchant accounts? But all a homeless person needs to beg for Bitcoin is card with a QR code!
Interestingly, you could be describing Dwolla there with each of those as well.
No. Because Dwolla is not available here in Canada or for that matter in Spain or Uganda. M-PESA for example has the same problem. It is not available in the United States or Austria for example. Also Dwolla has already being sued over chargebacks.