I think PayPal is reaching a critical point. Prior to this point, I felt like I needed to justify my use of PayPal, especially the fact that I have a PayPal debit card, and use PayPal like a bank. People look at me cockeyed and wonder how I could trust them that much (not to say that I should). Now, I feel like the tides are turning; maybe people think if they don't have a PayPal account, and I want to pay them that way, that they should get a PayPal account, rather than tell me that I need to pay some other way.
Well, really I'm less sure that PayPal is reaching a critical point, though my dance instructor did get an account just so I could pay her that way. But more interesting to me is the idea of defining a critical point in this way, where prior to it, people feel like they need to justify using service X, and afterwards, people feel like they need to justify not using service X. I recall Facebook reaching this point for me. At some point I felt like I needed to justify not having a Facebook account, and that's when I got one: it was just easier, and not a battle I wanted to fight.