Unfortunately, this will probably do more harm than good to PayPal. Innocent, phishing-aware users will be denied access. They'll just use some other payment method. (I'll point out here that iTunes allows PayPal payments, there are Mac users who like iTunes, Macs feature Safari ... you get the idea.) I imagine some users will boycott PayPal and use Google Checkout (for example) instead. Google can issue refunds for phishing because of its vast financial resources, as they do for click fraud.
These companies don't get it. To fight fraud, you must fight the fraudsters. Team up with security experts who study botnets, etc.