Difficulty is all a matter of what your goal is. Games tend to be easier these days because that is more accessible and they design their games around different psychological hooks than things like flow. Big Triple A games tend to focus on the experience. The game shouldn't usually be hard because that only stops you from seeing their best work -- their highlyc cinematic action set pieces.
Free to Play to Play games on facebook rely on psychological addiction hooks to keep people playing (and hopefully convert them into paying customers). For their purposes, difficulty is not necessary and if it exists, it should be a fake type of difficulty meant to trick the player into thinking they're being clever (which is a very very strong psychological hook when done right).
Of course, in the triple A, you got games like Bayonetta, or even more extremely, Demon's and Dark Souls. Dark Souls, despite it's crazy difficulty, sold an ass-ton of copies, because both games new how to craft an amazingly challenging and rewarding experience (See: the psychological state of flow again). I personally don't find those games to be as absurdly hard and soul crushing as people make them out to be (though they are still very hard), the idea that players THINK that adds to their mental reward after they succeed at a task. If you can get a player into Flow and have him leave Flow to pump his fist give a victory scream, well, you've done good. That's part of what made I Wanna Be the Guy work.
Another bit on this is, by definition, you are an indie/small tiem developer. Wide appeal is not always the most optimal course of action. Often focused niche appeal can give a piece of work the eyes it needs to get noticed. And if a game flourishes in a niche, it gets exposure to the mass market.
So basically, there is no right answer for difficulty, but you should be deliberate in your decision. If you want to do something hard, just make sure it is fundamentally enjoyable. Because even if dying wasn't the player's fault (like what happens in the Souls games of IWBTG at times), if the player is sold on the experience, they won't care. In fact, they might even laugh about it.