Both. Games have become more properly tuned to our play styles as avid gamers. They've been designed to be beaten from the ground up. We have difficulty levels, and can ramp up the challenge if we desire, or bring it down to introduce newer players to the medium. We have grown so accustomed to controllers that it's very easy (or at least easier) to deliver a sense of conveyance, where your controller becomes an extension of your hands, and the developers have learned how to craft games in such a way that this is the best part of gaming.
But if you take an average gamer of today, put an NES controller in their hand and ask them to beat Battletoads, a game that was never really intended to be beaten without absolute mastery of the system, they'd be hard-pressed to, and even our "hard games" like Demons' Souls, we have far more margin for error then in those NES Hard games. Games in general are better designed. Some old NES games, even excusing those NES Hard classics, don't feel like they were even designed by people who'd ever played a game. The UI is impossible to understand, the controls (despite the lack of buttons) are ill designed or just plain weird, the difficulty is through the roof because of bugs or poor design choices (unlike Battletoads which was actually designed to be hard, at least in the states, to combat game rentals)
Games are a lot better at telling us what to do and how to do it (a detriment to some), or barring that, tend to be open enough for the player to figure it out on their own.
We have also gotten better though over time I think. Those of us who've been playing games for decades have a lot of past experience to help us figure things out, and kids, as always, are great at sorting these things out without years of experience, and tend to be the technically most proficient gamers, as their brains are a bit more fit then us old timers (although admittedly, I'm not even on the old spectrum when it comes to gaming, although I did own an NES before SNES was even a thing, so that can date me).