Video games were difficult in the old days not because gamers were "badasses" compared to the "soft" kids of today, but because arcades were the dominant platform for game developers, so games were designed to defeat the player in a short amount of time, and only by overcoming that did the player gain substantial value within the game itself.
American console manufacturers of that day, including notably Atari, used arcade games not just for straight ports to the Atari system, but as their primary design inspiration. So Atari games were very difficult even though as a home console there was no longer the logical (capitalist) reason for that difficulty to exist.
I'm not familiar with Nintendo's history, but whatever their design inspirations, they did not include arcades as a major source (though still an important source, such as in Mario Brothers' difficulty and "lives" and Donkey Kong). Children's toys and animation companies such as Disney were the likely inspirations. This vast difference in design philosophy led to vastly different games, and meant that Nintendo games were typically easier than Atari games, and could be played (on a single "life") for longer periods of time, more suitable for the console capitalist model of money up-front and zero cost per hour spent in the game.
Because Nintendo introduced the "long-play" design philosophy to gaming, they more than any other developer are responsible for the development of narrative in games, which was nearly non-existent in both arcades and Atari games.
Dark Souls isn't better *because* it's difficult, but rather it's difficulty matches it's design. It's difficulty is not based on what capitalism proscribes for it's platform, but rather on what is best for it as a work of art, at least to an extent (it still holds home-console RPG conventions firmly in it's design).
