Macintosh portability seems to follow an unexpected technology development.
A MAC became a portable, well luggable, when a bag was invented to allow a desktop MAC (SE30, vacuum tube screens etc) to be heaved onto a shoulder. The sight in the evenings of the senior managers bent over carrying the portables home for the night is one the best reasons for having close car parks. :-)
Today the MACs are smaller and perhaps lighter. Higher density battery technology and perfectly adapted A4 and airport standard sized carry bags make MACs normal travel companions. How often is the carry-on MAC heavier than the stowed luggage?