Intel and Apple aren't "enthused" because they want to delay the game long enough to get Lightpeak going, which is higher bandwidth (but just like ESATA has no power over the cable which will complicate the connections and doom the standard until that's fixed). But Lightpeak is overkill, and thus not needed as something better than USB3 and the connections cost even more money in devices and there is zero backward compatibility, all things which make it only a win for Intel and a loss for the rest of the industry. If Intel truly "innovates" like they claim they should be building a 1 year old STANDARD into their chipsets and stop playing politics with a standard that everyone else is supporting for over a year. Or maybe the government should get back on top of them about Antitrust behavior...
Even "slow" laptop drives exceed USB 2.0 speeds. USB 3 doesn't get saturated using just an external flash or hardrive, doubles the power delivery over the wire which enables more devices to use it, and lowers the overhead on the CPU in the process. Using expresscard to deliver USB 3, only gives you half of the top rated speed IF the expresscard uses pci-e, because it's only a generation 1 x1 port in expresscard. However the alternate interface of expresscard is USB 2.0 in which case you won't get any speed boost at all. In either case you are getting short changed somewhat by going the expresscard route to USB 3. And moreover, you can't get the increased power from the expresscard solution without also plugging it into a USB 2.0 port on top of the expresscard connection. That makes it kind of kludgy.
Now half top speed 2.5Gb/s is still more than most flash and hardrives are likely to saturate, so the speed won't be a huge problem till high end SSD's start getting that fast, but it is still a limitation as the laptop gets older and the standard evolves. Built in USB 3 would give you full speed, full power and be far more ideal. HP, Sager/Clevo, and others have all put USB 3 into their machines, so the time is right to finally step up and get this standard into a new design of the M17x and M15x.