It is just the better way to go about it. By having people opt in it gives the websites control of their content. Some people will not want to have their videos rebroadcast in such a manner, and there may even be some copyright issues there. By doing it this way, Apple avoids any legal hassles, and also keeps web site and content providers from having to come up ways with blocking IOS users from accessing content just to prevent potential rebroadcasting.
Actually was a really good decision on their part.
I don't know.
I'm starting to get annoyed at systems that ask "permission" to do everything. I'd much rather the user be in control of that, and do any asking of permission if necessary.
Our tools shouldn't be making moral judgements. That's up to us to do. It's the same deal with HDCP, which causes perfectly good displays to be unable to show downloaded content, even though no one actually pirates video through an HDMI cable.