Search engines rendered that logic laughably naive, but I still think there could be some ancillary value in (noun).com as a recognizable and easily recalled domain name. I wouldn't overpay for one, but I wouldn't pass one up if the pricing made sense, and if I had actual plans to do something productive and value-adding with the name. (Buying domain names to squat and flip, under the "Greater Fool Theory," is a game I wouldn't recommend playing.)
On the other hand, the biggest non-technical challenge with buying a generic noun as a domain name is trademarking. Picking too generic a company name is setting oneself up for an uphill battle in today's trademark landscape.
Apropos of nothing, a domain like truestory.com is an interesting tossup. At the expected going rate of $25k+, it doesn't appear to make a lot of sense. But if someone were going to buy this name and develop it as a blogging or magazine format, I could see some value (again, barring trademark difficulties). As a writer and aspiring publisher, I'd scoop up this domain if it were priced within reason: say, the $1k-$5k range, tops. As a businessman, I'm a little gun-shy about the price tag.
As SEO has gotten more and more complex, exact match domains (EMDs) don't work quite as well anymore but are still a pretty big ranking signal [1].
For somebody worrying about long term brand appeal, an EMD might not make sense but for somebody launching a new ecommerce store or doing affiliate marketing EMDs are still a great asset to have.
Probably not. The only one that springs to mind is diy.com, belonging to UK DIY retail supplier B&Q.
But no-one thinks to visit that domain, so in literature they have to suffix it with 'the website of B&Q'...