As any software company well knows, there comes a time where you simply cannot support older versions. Try getting Microsoft to give you tech support on Windows 3.1, for example. But that line has always been a fine one, and Adobe has been pushing its luck of late. For instance, Lightroom 3 will never get a RAW plug-in update to support Nikon's D4, despite Lightroom 4 only recently shipping. But while the company may get away with that, it has been forced to change its tone with regard to security. A convenient update like D4 support is one thing; patching security holes only for those who buy your newest software? Well, that's reason to bark.
Responding to PR and public backlash, Adobe has changed course and now states that the outgoing CS5 suite will indeed receive security updates that were scheduled to only apply to CS6. The company's blog post now states: "We are in the process of resolving these vulnerabilities in Adobe Photoshop CS5.x, and will update this Security Bulletin once the patch is available."
Illustrator and Flash will get updated in time as well, with eight "critical" bugs to be addressed ASAP. Keep on fighting for those rights, folks. Maybe Lightroom 3 will get an update as well.