This is an interesting observation. I never used the "wand" function in Opera because, partly, it's named in such a way as to not appeal to power users at all. The name "wand" says "do something magically". Agreed that "wand" doesn't indicate what it does, which is another reason to shy away from it. It's such a generic term as to be useless. Literally anything could be behind the "magic" operation.
Another thing I forgot to mention which is quite important. It works well when your password store is encrypted. It allows browser to ask you for your master password when you are trying to log in to the page, not when you happen to visit page that password is stored. This makes feasible to use configuration where the password is forgotten either immediatelly or after few minutes. Having encrypted password store in FF or Chrome and not storing the password all the time in memory is essentially unusable.
Not sure about the newbie argument, yes it might be like that in the beginning, but you won't stay newbie forever you learn things. Also I'm not buying the minimalist argument, Chrome currently is one of biggest resource hogs among browsers.
Anyway at least provide option to enable such behavior. On Firefox I use Secure Login extension to emulate that, but it doesn't work as well as Wand did.
I wouldn't bother trying to work out some weird button, I'd just manually type my details again and again into every form and feel annoyed that the browser isn't remembering them like other browsers do.