Some are,
some aren't. The reason a lot of twenty-somethings recall 80's games as being more difficult than today's offerings is simple: we weren't very good at them.
Take Contra 1 (NES) for example. Notoriously difficult at the time of its release and dubbed
The Hardest Game of All Time by IGN*
† as recently as March of this year, this game, my wall, and the laws of physics joined forces to claim the life of my NES Max controller, a death that went unavenged until Thanksgiving break two years ago. I was bed ridden with the flu, and even through my fever-induced vision blur, I both embarked on and completed my quest to beat Contra without losing a single life in the same weekend. It really wasn't that hard at all.
Our cognative agility and dexterity have come a long way since elementary school. I guarantee that the fourth graders playing XB360, Wii, and PS3 this morning will be complaining about the difficulty (and quality) of games fifteen years from now, warmly reminiscing about the exact same games we're ridiculing for being "dumbed down."
* : They also credit Contra with introducing cheat codes.
† : lol