True enough. Games that are hard to some extent are fun do to them being hard. X-com, Mordheim and battle brothers are games that I enjoyed because they had some difficulty to them, they really have little else going for them. You can add 2d platformers, rougelike, strategy, horror and to some extent shooters.

Where you can get away with things being to easy is movie games and story driven games. Even then having it be difficult makes the games better.