I like having different log ins for different things, but not for parts of the same thing. For example, Facebook has nothing to do with student loans, I don't need the same log in for that and I actually prefer it. However, I have a checking and savings account with with the same bank. I wouldn't want to log in separately to view them.
That said, I'd prefer one log in for Wii U's online system. Wii U Steam would be ideal, but if Nintendo insists on a single friend code system like 3DS, it can work as long as they lighten up and allow it to be highly customizable by the user/parent. If I had to log in for each online game I play (and potentially pay to play), I probably wouldn't play online often, even if I could save the password because I'd still have to keep track of them all. I don't think Nintendo is going down that path. Their current cryptic comments don't concern me either. They'll reveal it in depth when they're ready and the comments are cryptic because they're not ready to talk about it yet. No surprises there. So far, it sounds like 3rd parties are optimistic and they probably know something. That doesn't enthrall me, but I'm given no real reason to be discouraged or anything. Not yet, anyway.