I think banks may be doing this to prevent money laundering rather than just to cause war against bitcoin. Though I can certainly see why the banks would oppose bitcoin as it could threaten their bottom line.
Agree with this. There is most likely a degree of skittishness on the part of banks (who are paying attention in any event) that if bitcoin were to stabilize and succeed they would be a threat. In the UK, which gets the most focus in the original article, the FCA has not taken a definitive position on bitcoin, which means that exchanges need not abide by anti-money laundering regulation. The banks, however, most certainly do. Could supporting exchanges undermine the banks money laundering responsibilities?
Probably not, but why risk it. To me, this shows that the UK, among others, needs to get off the pot and clarify the regulatory stance on crypto.