I think the title of the article is really misleading......, the author shouldn't be questioning the value of generic domains, when it is clearly obvious they are valuable. I think what might be questioned though is the value of generic non-commerce related domains that cannot be easily monetized, or where the ROI can't really be quantified. For example hell.com is a great generic name, but the type of person (or investors) who have the pockets deep enough to afford it are probably going to want to know how they are going to get a return on their investment. And a commercial company may shy away from branding hell.com just because "hell" isn't exactly a business-friendly word. So, it seems the market for that domain with the pockets deep enough to afford it might be somewhat small.
There's no question that good commerce related generic names will only keep appreciating in value, and it's absurd to question their value. And they do appeal to large companies with an existing brand who realize the competetive edge of type-in traffic, like: Bank of America = loans.com, Barnes and Noble = books.com, ABN Amro = mortgage.com, Hasbro = game.com, need I even go on?