Well, I doubt you would have the same opinion if it was the PowerBook or PowerMac line that got the silent update.
Customer A walks into the Apple Store and purchases a mac mini. Then goes over to the genius bar and has the genius set it up. The genius tells them that they have a 1.5 Ghz G4 processor, 64 MB of video memory, and can burn DVDs at 8x. Customer B standing behind them has what they believe to be the same mini, but when the genius opens the box they have a 1.42Ghz G4 processor, 32MB of video memory, and can only burn DVDs at 4x.
I don't know about you, but I would wonder why Customer A got a better computer than I did for exactly the same price.
If customers don't complain, and show Apple that this type of branding is unfair, then what's to stop Apple from mixing PowerPC and Intel chips in the new PowerBook or PowerMac line? Nothing.
Consumers like to know EXACTLY what they are buying.