before you had 3, the pro, normal macbook, and the pro.
You realized you just counted the Pro twice, so by your reckoning you had only two choices before the MBA.
The bottom line is if you don't like the line up, no one is forcing you to buy it, unlike what your title states. You have a choice of a "pro" laptop that comes in 13" or 15" sizes, or the very portable and relatively inexpensive price point MBA which comes in 11" or 13" sizes.
If you wanted a the MacBook back, but price point would you want it to be, what configuration would it have, that would not cannibalize the sales of the lines?
Simply put there's no room in apple's line up for a different computer line, they overlap quite a bit as it stands, just look at the 13" MBA/MBP. Can you imagine if apple rolled out another 13" laptop what would be the draw for that?
Don't forget computer sales have been declining by and large, so apple shouldn't be creating more computer models on a sector that is showing shrinkage..