I think the price difference may be accountable for in the specs. Most of today's netbooks come with spinning drives, and an SSD upgrade would cost $50-$100 more.
The Chromebook only has a 16Gb drive, so it'll be something similar to the little SSDs found in a number of netbooks two years ago. These suffer from very poor write performance (and not great bulk read performance) but are perfectly adequate for the sort of IO load a Chromebook will impart.
Maybe they are using better models (things will have moved on in the last two years) but they'll probably still be cheaper than a spinning-disk drive. Comparing a 160Gb spinning-disk to a high-spec 128Gb SSD would show a considerably price difference against the SSD, but these are smaller, slower, units. Two years ago the 8Gb SSD Acer netbook I bought was cheaper than the platter based drives (1200Gb IIRC), I expect the same to be the case here.
I dunno, spinning disk drives are ridiculously cheap these days. 160GB Laptop drives run ~$40 USD. The same price for SSDs will get you about 8GB of storage. It's just not comparable.
It might depend where the price breaks are. If you are buying one or two at retail then you are probably paying a large mark-up for the buzzword "SSD". Buzzword mark-up is not as significant if you in the market as an OEM buying in bulk.
Instant On really benefits from the fast sequential times and random cache hits from the low latency/high IOPS. I would imagine there is a lot of paging on a low memory machine.
The first generation macbook air users said that the SSD made up for the weak CPU in day to day use.
SSDs don't break if you drop the computer that they're in, throw it on a bed, or otherwise treat it badly. HDs do. Reducing the failure rate of Chromebooks is almost certainly worth it.
