While generally it is true today's games are easier, I'd say it's not necessarily a bad thing. Due to various technical limitations and overall the gaming industry having not evloved as much as it has in the last decade, older games were sometimes difficult in very frustrating areas. Since most games were mostly very linear and one-dimensional the gamemakers didn't have much room to try and make challenges vary in their nature. At some point you might have this extremely long jump you have to complete in a platform game; then later you might have an even bigger one, which basically leaves no room for other gameplay other than just trying to jump even further.
What I'm saying is that older games usually achieved difficulty in such a matter you were sometimes bound to fail anyway (trial and error).
Today's games, however, seem to be more rewarding in that when you do things right, you can succeed right away.
That said, however, what I think today's games don't do enough is the punishment for failing. Older games (very old in this regard) only had a limited number of lives, probably no save function, so you had to always try hard to survive. Today this has changed, because you're almost never punished for failing and that's something game developers should look at.
I'm currently playing Warhammer 40,000: Dawn of War II and it has a nice system where you can only do one mission per day. If you fail, you can repeat the mission, but you'll lose a day and the enemy will grow stronger. If you do good on a mission and gather enough points you are awarded an extra deployment for the day and can do another mission on the same day. I don't know if this has any impact other than my score in the end, but nevertheless it always makes me try hard to complete a mission and not just spam Restart every time something goes wrong.
Lets take Mass Effect. There's really no punishment in dying in that game other than having to do some parts over again. However, even though that is the case, I do find the game difficult. And mostly in the sense that I have to think to survive; I can't just blow through every enemy without worry. And at the same time, if I do take bad guys down it feels like I actually did it right - for whatever reasons, perhaps using my skills in the right order or giving my teammates the right commands.
Edit: just to clarify I was mostly talking about game mechanics and not necessarily puzzles or mindgames. The latter two haven't been so big in later games anyway I think, mostly due to their main genres falling out of popularity. Games today also tend to explain everything to detail, whereas before you mostly had to figure stuff out yourself.