Again, speaking in terms of US copyright law only, you have the same right to rip a DVD onto your computer, and even subsequently put it on your mobile device, that you do a CD. Space shifting and time shifting for personal use in the US is 100% legal and has been tested in court for over two decades. I have the legal right to take all my VHS tapes and burn them to DVD or put them on a media server in my home, for example, just like I have the same legal right to make mix CDs or copy custom playlists of songs onto my Shuffle.
Now, do some people want to step in the way of this? Yes, of course. Movie studios would love to sell people the same movie as many times over as they can (VHS, DVD, Blu-ray, digital download, etc.,). And because they want customers to keep re-buying the same thing over and over again they lobby for legislation like the DMCA and to keep extending the time limits for keeping IP out of the public domain. The DMCA contains provisions that basically do an end run around US copyright law and deny the end user their legal rights established by US Supreme Court and at least one Act of Congress and you think this is a good thing?
Lethal