Andrew Smale doesn't seem to believe any of it is worthwhile:
Role playing games inherently have more hours of gameplay embedded within them - by the time a roleplayer has finished his latest adventure the FPS gamer has perhaps finished two. As a result player involvement goes much deeper - so deep that the resentment towards its lack of quality is enough to keep trudging through its poorly constructed game world or slipshod storytelling.
Clive Thompson seems to be operating under the assumption that however much gameplay a game might have he should finish it before the next must-have game comes out, though it seems to me that 40 hours is perfectly doable depending on how you spread out those hours. If you give up and then go on the the next distracting shiny thing, then, it seems to me, that this isn't a problem with the game.
Some games do seem to make progress unreasonably difficult though. This weekend I went back to playing Mercenaries to see if could get past the second boss level to get to the second half of the game. After a fairly frustrating hour or so I manged to sneak past everybody and rain down destruction on all the right things (and one wrong thing, but the bonus for not killing the boss wasn't balanced by the need to just move on). The game is now fun again as it has returned to its more sandbox styled central gameplay.
Also, there are plenty of great 10 hour games. Prince of Persia, Beyond Good and Evil and Psychonauts are three games with great story-telling, wonderfully realised worlds and fun characters. They all took around 8-12 hours to polish off and, while they all had their moments of frustration, I generally felt satisfied at the end of them. The myth of the 40 hour gamer is surely that a game must be 40 hours long.
One recent game that had an interesting compromise on this was The Godfather. The main story missions could be done within a few hours (more if you padded them out by taking down one family and doing all the hits) and then you could extend this by collecting everything and taking over the whole of New York. So you have a 10 hour core with an extra 30 hours gameplay for those who feel the need to accomplish everything. I find it fun, too, for short bursts of random violence. It's not a perfect game and it can feel repetitive in the long run, so as an experiment in appealing to two types of gamer it does fall somewhat short of truly satisfying either, especially with the problem that the story missions never become particularly testing.
In the end it may be we just have to accept there are some games we will never finish.