From Teh-chen..."The problem with ultrabooks is that generally people don't require them--they're nice-to-have items, but not really a mass-market computer. Anyone who expected them to do well--I mean, compose any significant number of computer shipments--probably didn't understand the market in the first place. They're excellent for mobile people who will pay a premium for that mobility without taking a hit on specs. Otherwise, they're not appealing in any way."
Agreed, plus manufacturers haven't yet realized that an important part of that mobile demand are working professionals from IT, visual/audio industries, counseling, sales, commuters, etc. areas... that require several features not yet implemented, namely; all-day-work battery, reliability in terms of serviceability & upgradeability, and finally, the inclusion of versatile pro-connectors like ExpressCard or Thunderbolt.
Without those, as mobile workers we will not take unable-but-light laptops into the road and will continue to rely on limited functioning while on the move (pendrives, smartphones, tablets) or seldom take away the office /home our reliable professional laptop lines like Lenovo, Dell or Apple.