I kind of agree with you about the Game Boy Colour/old GB argument.... but the rest of what you said is very obviously wrong.
The only problem with the GBC/GB thing is you can't concievably split the software up, ie there is no way of knowing how many of a game sold for the GB or the GBC. Thus they are essentially the same system, but I think there were enough GBC games only to justify it being different.
The difference between the two handhelds is the closest you can get without it just being a hardware revision though.