Firstly, there's a difference between ripping a DVD and downloading a pirated movie.
More importantly, DVD ripping is far, far from a mainstream activity as evidenced by the tens of millions of DVDs that are still sold every quarter. The reason it is not mainstream, like CD ripping is mainstream, is because of DRM. Anti-DRM measures are not built into operating systems or the most prevalent player applications. The studios regularly mount legal challenges, many of which are successful, against application developers that do build in anti-DRM measures. The result of all of this is that the vast majority of users do not have the tools necessary to rip DVDs. For some portion of those users who become inclined to try it, they can find a tool that does - and then they can encounter Sonys ever evolving intentional error DRM strategy whereby the tool the user has no longer functions and either needs to be updated (assuming the often fly-by-night developer is still around) or replaced. Effectively, the annoyance factor is increased enough to dissuade the casual DVD ripping user from continuing with the activity.
Hence, intentional errors has increased the annoyance factor in ripping DVDs and therefore somewhat decreased the prevalence of ripping.