I think games were harder back then but at the same time they whole way they were was designed to keep you patient enough to keep trying. I know there were more than a couple games where the whole level was in plain sight all the time. If it was something like Castlevania for example, I'd say each area of that game was 3 or 4 screens long at the most. But something like Solomon's Key was one screen per level I think. Basically if you think of it that way, you can survey the entire level and figure out exactly how you're gonna do it before you even press any buttons. In newer games you don't usually come across that because you're limited to whatever perspective the game gives you. Sure you can have a mental map of the level if it's an FPS but the enemies don't have patterns like they did in the NES days, and even if they did it would be annoying as hell trying to figure them out if you didn't have a nice overview of all the guys moving at once. But then again I haven't played too many of the 3D platformers other than Mario 64 and crap
But I think the games are easier because they changed from this sort of "planning" gameplay to a kind of "quick reaction" gameplay (like in FPSes particularly. Not to say that FPS games are devoid of strategy but more of it is OH SHIT GUY IS SHOOTING SHOOT HIM FIRST when the old games were like 'guy shoots at regular intervals but if I jump this way I can dodge the very slow-moving bullets"
So I do think the new games reward quick reaction time over figuring out the right way to approach a problem which is inherently harder and probably involves a lot of that CRITICAL THINKING I've heard so much about
Again I have to say Resident Evil 4 was awesome because it had the quick reaction kind of stuff but it also requires the player to keep track of what the hell everyone's doing (like make sure there aren't any freaky guys with chainsaws coming up behind you) it isn't exactly the same as figuring out the exact jumps you need to do at what time but in the Mercenaries Mode you really got a feel for how hectic the formula could get as more bad guys get thrown in there
But uh like I was going to say in the first place I think it's kind of good that games are generally easier because if the games were ridiculously hard it would really hurt the flow of the story. Like I remember how cool the original Ninja Gaiden was and I loved the cutscenes but after a certain point I couldn't get any further and see more of the story. So after a while it was like no tidbits of story + frustrating and kind of small ugly stuff on the screen = not much reason to go on. On the other hand games are getting so good-looking the whole thing feels like a movie unfolding so maybe it's not so bad
I remember a while back I said how Dragon Warrior has no excuse for having high encounter rates anymore because at least in the old games your 'target' was in plain sight, like a staircase or whatever. But in Dragon Warrior 8 the world was so damn huge you're not really heading towards anything certain and to have AIMLESS WANDERING get interrupted is not very constructive gameplay
Edit: Dragon
Quest 8 - when the hell did that happen

Edit: But I think we could make games harder without being frustrating, it would just have to involve a different kind of gameplay imo - like I was saying Resident Evil 4 required you to keep track of lots of stuff on the screen but not to the extremes a space shooter would. Maybe somebody has tried already but if someone could recreate how hectic the 2D space shooters are but in full 3D without making the player chalk up their losses to a bad camera system/etc would be pretty amazing (also 2 1/2-D doesn't count btw - I mean like Starfox but with 1000 ships at once and they're all INSTANT KILLDEATH)