I think there are a lot of solid arguments there, but I don't think that you can generalize that sort of thing. Some games need to be long, and others don't. Padding every game out to lengthen the experience does indeed cheapen them. But at the same time, aiming for tiny amounts of time with every game seems like price gouging to many consumers, and doesn't really give the developer as much space to do interesting things in.
If you've got so few ideas for a game that it's only 5 hours worth of gameplay, to me that sounds like either a pretty shallow game or else something that is very story/setpiece driven. There's a place for story/setpiece games, and those can be pretty cool -- short and sweet can really work there -- but many B-grade games from AAA studios that are short don't really fall into that category. They're just uninspired, as well as short.
So I'm not sure what the takeaway here really is, though the article was interesting. It's good to see that it's being recognized that games shouldn't be padded out, but at the same time when they start shortening games that need to be long -- say, epic RPGs -- that's not doing anyone any favors, either. I'd rather have less graphics fidelity and a more awesome and lengthy story/gameplay. A lot of the stuff on Nintendo consoles really meets that criteria.
