Depends on how you look at it.
RPGs are as long as they've always been. Heck, I go back and am surprised that I can beat the RPG greats like Chrono Trigger and FFVI so quickly (30hrs) which seems 'short' by today standards.
And outside of RPGs, there's no comparison. Shooters are quite long, but most, if not all, have multiplayer which makes said games much longer, and offer more replay value. Heck, some games like Call of Duty 2 still have an active community on the X360, so the replayability is infinite.
Ultimately, your argument offers no actual comparisons. Go back and play The Legend of Zelda 1. And then play Ocarina of Time, then Twilight Princess. Guess which one takes the longest to beat?
Final Fantasy is the same way - I was maybe halfway through XII by the first time it took me to beat IV.
Fallout 3 - 40hrs in, and halfway through the main quest, and over half of the optional quests.
And those are just a few of the quick examples. Games are getting longer. The fact is that, 20 years ago, many games were so incredibly short that many attempted to "master" runthroughs which increased replayability. Now, the simple act of beating a game takes 10hrs and is considered short.
Back from the dead, I'm afraid.
