My guess is that it dates back to the Shockwave days when:
1) Flash was used solely for static & animated vector graphics, and
2) Browsers didn't have the zooming features they do now<p>We take Cmd+/Cmd- (and whatever the Windows bindings are) for granted nowadays. Browsers didn't always have the ability to scale things up and down for us, so it was a nice feature back then.
On a related note, has anyone found the different quality settings for a flash app to have any effect? I used to browse the web on an ancient G4 powerbook that would choke under most flash apps and movies, and lowering back the quality never had any impact for me.
It's because Flash is often vector art, and you can zoom to see details in some cases (without degradation etc).<p>I know of a fashion industry website where this functionality is expected. Makes me shudder!