I think the Macbook and Macbook Air is much worse, but I suppose it's unclear if both are currently active lines.

Agreed, and the solution is stupidly simple -- just swap the names! The whole thing is so un-Apple.

I partly understood it with the "first"-gen New MacBook; it was experimental, and they wanted to give it this kind of minimalist-mystique of flipping the naming convention where this forward-looking device was now simply "The MacBook". But why does it even still exist now that the other ones have adopted most of its features?

At least in that case there are three letters of difference, instead of one :P