Again, most of the people who buy MBA's are not going to have it as their sole computer, meaning that short of buying an external drive, they could easily use the Remote Drive feature for something like an OS reinstall.
But seriously, from a comment like this, you'd think that Apple was the first company to release a machine without an internal optical drive.
Again, do you think Lenovo ThinkPad X61 owners are left helpless when they have to do an OS reinstall because their machines don't come with optical drives either?
And as I mentioned above, Lenovo's own solution is a drive bay that costs $100 that requires you to also buy a $200 docking bay, although you can just as easily buy your own $99 USB drive from somewhere else to use.
Frankly, Apple has gone farther; first by just offering the $100 drive directly without requiring an additional $200 add-on, and second by debuting this "Remote Drive" function, which Lenovo certainly doesn't offer.
But seriously, if the ThinkPad X61 and its owners can deal with it, and the X61 is one of the most popular and praised ultraportables on the planet, I think people will figure this out with the MBA as well.