I don't think most people were looking for a laptop that was marginally smaller than existing Airs. the AIR itself is already small, light and super portable. shaving off 1/2lb and a few mm's doesn't suddenly make it more portable.
However, losing your ports, performance, keyboard is something that may not make this worth a $1500 laptop.
I think the level of dissapointment comes because they could easily have put a retina display in the MBA, swapped out one of the USB ports for USB-C and put in the force touch trackpad,
and still charged $1400 for it, and it would impressed the entire world. I would have bought one for sure. this is really what I think people were looking for