The amount of people buying off-region DVDs is awfully low. There are a thousand betters reasons to reject DRM such as not owning your product anymore ("That iTunes music ? Yeah, they can revoke your access at any time.").
It's the same thing as "Oh I'm sure the government COULD access all my data, but why would they want to?"
Region-locking affects more people than you might think, just not with DVDs anymore. Most of the world using reddit/hackernews/the internet is constantly faced with the frustration of clicking on a youtube link and seeing the copyright notice that says the content is restricted to US-only.
It would be nice if it told me which regions were allowed, so I knew which VPN I should use :P