How difficult should games be?

Gamer Limit writes: "Difficulty in games has always been a reasonably contentious issue amongst gamers. Many would be quick to cry foul, exclaiming with much anger and remorse that games have become too easy, filtered and stripped to fit the time and attention spare mainstream gamer.

While others, probably more likely to be a little bit more balanced, would generally say that game difficulty has become less of an issue – as titles become more focused on multiplayer, and developers start to play around with multiple difficulty modes and scenarios.

But that leads to my question – How difficult should the average game be?"