> But you might use a the same login for your blog as you do for your online banking
That is a completely different problem that using https won't solve. It's like building a ship with a hole at the bottom and having a high throughput water pump.
Yes it will, because passive listeners on the network won't be able to catch your password. Only your blog and your online banking will be able to get it, as is intended.
Also note that as tech-savvy people, we have more responsibility in ensuring our users are safe, even from themselves. Sure, the better thing to do would be to educate everyone so they don't reuse passwords. But it will take time, and using HTTPS in the meantime decreases the chance for them to be pwned.
Most people wouldn't be comfortable with a stranger looking over your shoulder while they logged in. This is the same thing, only you don't think about it.
These things are ALL rare, but why would you want to expose yourself to this?
SSL everywhere is also about improving security for those who don't realize that they might be engaging in behaviors that compromise their own security.