Earlier quoted context omitted.
There is the Air line for light weight laptops for normal people. I would think that the word Pro signals that this computer is for people who want to do stuff with it beyond what is provided up front.
This is the crux of the entire issue, crystalized perfectly. If you are going to carry multiple product lines, then why would their features converge? I see no reason to get into the closed vs open debate - this is Apple we're talking about. But why would they turn the Mac Book pro into a MacBook Air with higher specs? Why not get rid of all the branding distinctions and let the consumer spec out the machine, with a…
They didn't. You can still get an old-style macbook pro with updated internals. They're offering a new option that looks a lot like a MBP-Air. Doing essentially what you seem to suggest: giving people a choice of a new thing and not taking any old things away.
And if/when most pros demonstrate that they don't care about the modicum of hardware-accessibility in the old-style pro design, Apple will simply be dropping the product that its customers do not prefer. As it always does. As it did with the 17" MBP. A beast that increasingly few Apple customers had any interest in.