Yeh for me it was all about convenience, I could have done the bank transfer for free but it was more difficult (international bank transfers from UK banks tend to require a lot of additional information). For me 10 euro is nothing, so wasn't fussed to pay a little extra to to all the hassel of having to deal with my bank. For people who care about 10 euro, they can still pay using their bank (and for most people it will be a darn site easier to make the payment than my bank makes it).