I really don't think there is a licensor conspiracy to make games easier so they can sell more. If anything, they're perhaps making them longer! Either that, or my skill is going with old age...
Take a look at many of the old classics. I remember beating the Ninja Gaidens, Mega Mans, and many others in an afternoon. The Castlevania's were a bit longer, but easily done in a day or two. Even RPG's used to be around 20 to 30 hours to beat. Now, if I can beat an RPG under 50 hours I'm surprised!
In my opinion, it's not the length of the game, but the quality of the game that has diminished drastically over the years. Back in the day (I've always wanted to use that phrase
) it was very common to play a game over and over and over. But now there is so little substance to games that once you beat it, you're done. So much attention is given to graphics, that the little details - such as story and replayability - take a back seat.
Of course, I'm speaking in generalities.