You can blame the people who totally refuse to even update their software for this.
The whole opinion of the internet is that updates do more harm to your system than they do good. Microsoft ends up installing gigs and gigs of drivers and all the fixes just pile up. So people have grown to hate Windows Update and even go as far as disabling it.
These same people are the ones who probably bombard companies with support tickets when something stops working or things go wrong. Their hard drives are a mess too, because when system updates are done, so is background cleaning of caches and other stuff.
Since there are many, many, many individuals who refuse to believe the security risks, this is where it has ended up - Silent updates and disabled plugins. Maybe it doesn't look like a good idea from your end, but it's better for companies like Adobe. Because people getting hit with malware with versions that were replaced month ago is just bad press. It just adds to the many reasons why people hate Flash so much these days.
As for Adobe's URLs. They have many of them, and blocking them won't really matter as they're always adding new ones.
