As far as games go, i think sometimes less.. is more. Even if the game you're making is really complex and it's got a whole bunch of cool features that you're really proud of coding (or whatever), you have to try to make it look as simple as possible. The last thing you want is the player to be confused or intimidated by your creation.

All you need to do is look at most commercial games to see this bit of wisdom in action. In indie games, where the creator has less credibility and the user is more likely to give up on your game for the slightest reason, it is even more important that your game is as user friendly as possible.

Very true, and often overlooked.

By me.

Definitely, especially if you're trying to appeal to a certain audience or improve marketability of your game. But keep in mind that experiments in complexity are also a great way to break new boundaries in game design, and even if they don't result in very playable or great games, sometimes what they teach you about design can go on to prove more than worthwhile in the next project. Look at Dwarf Fortress, for example; I can't play it, because I forget completely how to every time I load it back up, but I find it a fascinating and notable experiment in game development.