Well, people are obsessed with long games because developers are so determined to keep making them shorter. Me, I'm thorough, don't like to leave areas unexplored or (assuming my character can handle them and what I'd have to do isn't thoroughly rotten) quests undone (secrets and easter eggs... depends, if they require doing weird things that don't quite make sense in the context or pixel hunting, I probably won't find them), so back in the day I generally played games for far longer than the listed duration. In recent years, however, I see listed durations that, while still shorter than what they were 10-15 years ago, are actually longer than even I take to finish, so have to wonder who comes up with those numbers and how these days.
Bottom line, if I'm paying for a game and don't get at least some 50h out of it (being thorough as I am, but straight playing, not counting reloads, so use save timer for those that have one, and strictly singleplayer and a single playthrough thank you very much), I'm not a happy camper. And if it can get towards 100 and still keep itself from getting tedious, even better. Just get a few games a year, after all, so they'd better last.
So the best thing is a great 100-hour game :p Past that, yeah, I'll go for a great 50-hour one over a modest 100-hour one, but as for the "better make a good 10-hour game" remark, nope, not unless it's freeware, that's waaay too short to warrant buying, no matter how good it is. (Though, of course, for those with the audacity to release such bite-sized games on a commericial basis, there are ways to play them as if they're freeware :p)
