Not at all. When the iMac came with CD drives, operating systems were already available on cd-roms. How many copies of OS X and/or Windows have you found on USB? That's the only "drive" present on the MBA, and it isn't even new (which the CD drive was back when the iMac debuted). No, this is more like the iMac coming without a floppy or a CD drive, and Apple asking users to buy an external to reload the OS.
The only OS that you can't install over the network is Windows. This is purely a problem with putting windows on the Macbook Air. You can install OS X onto the Macbook Air over the network just fine.
I repeat, this issue is only for people who want to put Windows on their Macbook Air.
First of all, I question putting yet another OS on an already small hard drive. The minimum boot camp partition is 30 gb. So assuming you have the larger 80 gb hard drive that leaves you with 50 gb left, or about half the hard drive for your stuff on your OS X partition (when you take OS size and free swap space you should leave/~10% of the drive). The Macbook Air is limited so it can be super thin and light. Hard drive space is one of those limitations.
Second, a lot of people whose opinions I've read are looking at installing Windows on an external (due to reason number 1). If the install is happening on another hard drive you can just take it over to another mac and install it from there.
All these shrill screams about the Macbook Air are coming from people that need to step back and think for a second. Do you want the Macbook Air, or do you want the
Macbook AirCraft? Do you want a Macbook Air, or do you want a Macbook (want an affordable laptop)?
Really. You might as well complain that Apple makes xserves. Are you going to buy an xserve? I'm not. I don't need a server. Why are they making a server? They should be making something with all those features tailored to my nebulous needs.
So, can we all please take a deep breath and stop flipping out over something as silly as a computer being released that doesn't match our needs?