There is lot of talk about the diffuculty settings of games. Especially to those who play at easy or normal level. The debate is about receiving the right gaming experience and also how games ought to be played. Same kind of debate as should you put milk on your black tea or sugar in your coffee, which is more enjoyable and so on.
It really depends on the game, and for what reason you are playing games in your leisure time. If you're doing job that requires most of you're energy, you aren't going to play games like Touhou on lunatic difficulty. But there is something to lose if you play games which are designed to be for the hardcore players, unless if it's story driven game.
Story driven games are more about choices and interaction, hence high difficulty isn't necessary or even good for games which lack proper gameplay.
I recommend putting the normal difficulty always as default, and then playing through the game to a point where you have succeeded to about 20%. Then you should consider raising or lowering the difficulty. Of course the game hardens as you go, which can be quite enjoyable. As you know that you are developing as you play.
Frustration and anger isn't always bad. Games that make you go through different emotions are usually the best games you play, since they make you immersed and make you feel like, you are part of something great.
Enquire to the different settings of games and find the best preferences that suit you, don't care about others. You enjoy games for you're own sake, not for the sake of others.